# My Rancilio S27 refurb



## tictok (Dec 1, 2013)

Righty then - time to get deep and dirty with my beloved S27.

This thread is half for me to keep track of things and ask questions, and half incase any coffee geek finds this interesting.

I've decided a reburb and deep clean is long over due - wish me luck!

There isn't a specific ranciio thread so hope posting in here is okay.

*Background*

My Rancilio S27 was manufactured in 1996. I bought it from a small bar in North London about 7 or 8 years ago.

I've used it daily since (approx 3 - 5 shots). I originally plumbed it in though an in-line water filter then after shuffling the kitchen about a couple of years ago I've been using a reservoir tucked behind the machine filled every few days with filtered water instead.

Apart from back flushes, descaling and occasional group head rubber, the only maintenance I've ever done was to replace the original pro-con pump as it had a little leak.

Last time I had the top off (about a year ago) I noticed a little water and steam escaping out of the safety valve on top of the boiler whilst it was heating up but didn't do anything about it.

It's been running fine, but during the last few de-scales I've noticed some occasional dodgy coloured water and a few tiny 'gritty' bits coming out of hot water outlet and steam wand when trying to cycle the water in the boiler. I assumed it was perhaps due to descaling and left it at that.

Anyway, I'm moving to a new house in around month so instead of being pro-active and packing stuff I've decided to pro-crastinate and refurb / restore my S27.

The previous owner had painted the original red panels a dodgy blue/green, so as well as sorting out the innards I thought I'd restore it to it's original red finish.

I've decided first thing to do is to move it my work bench, strip down, label the wiring loom, and remove the boiler.

Here goes...


----------



## tictok (Dec 1, 2013)

1) On my work bench this afternoon, ready to go.










2) Side panels removed. Easy to see original red colour underneath










3) Naked and labeled-up. I taken photos of practically every angle and cable as haven't been able to find a service manual or decent schematic.










4) My little helper (my youngest) popped in to see what I was up to and help out.


----------



## tictok (Dec 1, 2013)

Anyone know where I can find a service manual or set of schematics for Rancilio S series (specially S27)?

Also any good recommendations for spares (gaskets, seals, wiring looms or suitable wire to make my own etc etc)

Thanks

p.s. I've posted a bunch of pics of the strip-down of my machine so far, but the post needs moderating by a mod first...

Glenn: Approved post


----------



## tictok (Dec 1, 2013)

Thanks Glenn.

Next: Down to the nitty gritty

1) View of top of boiler.

The leaky safety valve has started to make quite a mess over the past year or so.

Also to the right of the boiler-top in this pic it looks like there's been a little leaking or corrosion. I think that might be the water level sensor. Guessing at this stage though.










2) Boiler removed and back in the utility room. Hmm. Not the best state.










3) Splitting the boiler for the first time. Hope I'm doing this right.

Was expecting to see some sort of gasket or seal in there.... nothing.










4) Uh-oh, whats this... poured out water in boiler and lots of gritty deposit flowed out too.

Stuck my hand into the boiler. There's a layer of this, somewhere around an inch deep at the bottom of boiler. not good.



















5) Internal walls of boiler - less lime scale than I thought there might be. Not pretty though.










6) Heating element, heat exchanger, water level sensor, inlet and outlet.

Again, not as scaled up as I fear it might be. Wasn't expecting the really dark deposits though.


----------



## tictok (Dec 1, 2013)

So, its obvious to me a great deal of de-scaling and cleaning up is required.

I have a few questions:

What's the best thing to use for cleaning the boiler and heating coil etc? Can I use the same for both?

Should there be a gasket or boiler seal? I can't find any trace of any. I'm removed a few other parts too... i.e group head assembly removed from boiler and no gaskets there's either. Just chucks of brass bolted to chunks of brass. There where a few O-rings I spotted here and there which I'll replace, but would like things to eventually go back together properly.


----------



## Padder (Dec 14, 2012)

Is that brown sludge limescale? Seems odd if it is that it's done that but the sides of the boiler and the element are relatively clean.

If it's not limescale then it makes you wonder what the hell is in our tap water


----------



## tictok (Dec 1, 2013)

Really not sure Padders. It feels quite gritty... not slimy... maybe a little somewhere between sludge and sand. All gone now though.

Like you, I would've thought that if it were limescale the heating coil and sides of boiler would be much worse.

Anyway, just got back with a job lot of citric acid so going to get a soak on. Going to soak the group head, brass tubing etc too. May as well do the lot while I'm at it. Bearing in mind what I found in the bottom of the boiler, should I remove the heat exchanger and clean that separately?

Whilst I'm 'deep' descaling I got a load of paint remover gel to slap on the side panels to clean them up so I can eventually get 'em sprayed or powder coated a nice red colour again.

---

After a little research, what I initially thought was a leaky safety valve turns out to be the anti-vac valve. I wonder why so much water was escaping from mine. It still closed / sealed once the boiler was up to temp... Boiler over full?



















Right, a little more unbolting to do and then I'll get descaling.


----------



## tictok (Dec 1, 2013)

Next up... all the copper and a little brass in the tank - weak-ish citric acid solution. Plenty of bits already had a soak in Puly caff.

This is after about 14 hours, just before I refreshed the solution










Meanwhile I've removed the wiring loom all seems in reasonable nick. Some of the plastic covers are a little brittle.

All the solenoids out, pump removed, electronic brain removed... just last few bits to go before I start work stripping paint and any rust of the chassis before priming and spraying.










Copper and some brass after 36 hours in solution (this evening). Will come up a treat with a little fine wire wool.










Heating element looking a whole lot better.










Boiler and HX back in the tank over-night. There's some stubborn stuff still stuck in the bottom of it.










Haven't got a pic, but after a messy evening with some evil chemicals last night the outer side and back panels are now down to bare metal.

Will hopefully have a S27 service kit and a few spare parts on its way to me shortly.

Tomorrow I'll hopefully be prepping the chassis for paint.

to be continued....


----------



## coffeechops (Dec 23, 2013)

Looks like the season for refurbs - just starting mine too (not a Rancilio though). Am also moving house, funnily enough...

Looks quite a lot like the scale I sound in mine. It dried a very pale cream/grey. Does it dissolve in white vinegar/citric acid?

Another thought, could the gritty stuff be water softener resin from the old filter?

Colin


----------



## tictok (Dec 1, 2013)

Hey Colin -



coffeechops said:


> Looks like the season for refurbs - just starting mine too (not a Rancilio though). Am also moving house, funnily enough...
> 
> Looks quite a lot like the scale I sound in mine. It dried a very pale cream/grey. Does it dissolve in white vinegar/citric acid?
> 
> ...


What machine are you having a go refurb'ing?

Most of the scale dissolved in citric acid bath in less than a day.

There's some stubborn really dark stuff that's taking a little longer to dissolve - currently in second bath, around 36 hours in total. Will leave 'till tomorrow evening - I expect most if not all will be gone by then. I didn't have that much citric acid, so went with what I've got. I occasionally check PH of solution with an old digi PH meter and its half way back towards PH neutral, so I reckon it definitely looses its effectiveness and needs replacing after a while.

It'll all be shiny by true time I"ve finished, although I reckon that's slightly OCD as no-one will ever see inside the boiler...

Good point about perhaps been residue from old water filters... they are full of some kind of gritty stuff, although they start life a much brighter / whiter colour than what I found in the boiler. Could be...

Cheers

Stef


----------



## coffeechops (Dec 23, 2013)

A CMA Lisa, ex-Costa. Have put up a thread on the Grinders|Machines forum (maybe the wrong place).

Did you try any of the grit you physically removed in citric? Might have pointed to it being scale or not is what I was wondering. There's a shot on my thread of the group-head-to-boiler cavity which has gritty scale in that looks a lot like a paler version of the stuff you found.



> It'll all be shiny by true time I"ve finished, although I reckon that's slightly OCD as no-one will ever see inside the boiler...


Ah, but you'll know it is shiny!









Colin


----------



## coffeechops (Dec 23, 2013)

Hi Stef, did post but seems to have gone amiss somewhere.

I'm refurbing a CMA Astoria Lisa SAE-1 (thread in the machines|grinders forum).

The colour does look like some of the scale I had - there's a pic over in that forum - was really wondering if you'd kept any so you could see if it fizzed in vinegar to give some indication it was scale or something else...

Colin


----------



## iroko (Nov 9, 2012)

Interesting post, look forward to seeing more pics.


----------



## tictok (Dec 1, 2013)

coffeechops said:


> Hi Stef, did post but seems to have gone amiss somewhere.
> 
> I'm refurbing a CMA Astoria Lisa SAE-1 (thread in the machines|grinders forum).
> 
> ...


HI Colin - nope sorry, didn't keep any of it... couldn't get rid of it quick enough, although it would be interesting to find out exactly what it was. My citric acid bath was too weak for anything to really fizz, however everything is back to shiny copper again now with the exception of a few bits of dark stuff obj the base of the boiler that's been very stubborn. One more night in the citric bath for that. Out of fresh citric acid, so can only hope threre's enough acidity left to do the job. The solution is fairly green now, so hope I'm not etching away too much copper!

Off to take a peek at your refurb now!



iroko said:


> Interesting post, look forward to seeing more pics.


Thanks iroko.

There's should be a bunch more pics I posted last night... post needs moderating first though.

Is there an easy way to add pics to a post without it having to go through moderation?

Cheers

Stef


----------



## coffeechops (Dec 23, 2013)

tictok said:


> Out of fresh citric acid, so can only hope threre's enough acidity left to do the job. The solution is fairly green now, so hope I'm not etching away too much copper!


Heat might help if it's only mildly acidic, roughly a doubling in reaction rate for every 10C rise in temperature I gather. I'm not sure the green is dissolved copper ,either - I thought it was dissolved copper oxide, so in fact you're not etching away any copper by leaving it in longer. I am no chemist though...

Colin


----------



## Padder (Dec 14, 2012)

You can use muraic (hydrochloric?) acid which will get rid of everything quickly but obviously needs a bit more care. Looks great when you drop a scaled boiler in and it starts fizzing away


----------



## tictok (Dec 1, 2013)

Looking like I'm going to need to stock up on either more citric or muraic acid anyways.

I managed to pretty much get the chassis prepped for painting tonight - no signs of any rust left. It was actually in better condition than I thought, any rust was just light surface stuff.

Just need to degrease before spraying tomorrow.

Once I'd finished that I came to check the boiler. Please to see that practically all trace of scale has gone... a few tiny specs in the bottom. Nothing a bit of wire wool can't sort out.

Took boiler out of the tank and drained heat exchanger that I'd left attached as could manage to remove previously. Didn't want to try too hard and damage it.

Anyway, once drained I noticed a bit of a rattle from insider the HX. uh-oh.

So took it into the garage, stuck the boiler lid in a vice and managed to open the heat exchanger. Even though it'd been soaking since sunday it was still had a fairly thick coating of lime scale. Much different to the stuff that was in the boiler. This was of the traditional lighter grey hard stuff. A few chucks had come loose causing the rattle I heard earlier. SO that's back in the citric tank again... will see how it looks in the morning although think II'll need to re-fresh the tank.

Good job I looked!




























Removed the old PTFT tape and gasket, so must replace those with new before putting back together.


----------



## iroko (Nov 9, 2012)

Great thread, keep posting the pics, look forward to seeing the finished machine.


----------



## espressotechno (Apr 11, 2011)

Beware, all you budding renovators out there ! Hydrochloric acid is evil stuff & needs to be handled very carefully.

Much better & safer to use diluted phosphoric acid (non-foamy variety), as it is less likely to eat your fingers off & doesn't attack copper / brass / stainless steel.


----------



## coffeechops (Dec 23, 2013)

Great to see it getting cleaner, please keep the pics coming!









Just taken my boiler apart and the colour of the scale is pretty much identical to the sludge you found, Stef...

Colin


----------



## tictok (Dec 1, 2013)

Thanks for comments









No fresh pics tonight - too busy!

Applied first couple of coats of paint to chassis. Couple more coats needed tomorrow. New pics then.

Also stripped and sprayed the metal mesh heat shield type part that runs underneath and partway up the front (near the drip tray).

Light sanding and second coat of primer on outer panels. Should I spray them their original red colour or do something different? I'm feeling a little inspired by Jeebsy's pimped up grinder paint job.

Still descaling heat exchanger in old fluid, it's getting there... about half scale gone now. It'll be good by the weekend









Everything else is scale free now, and half of the brass and copper stuff is now polished too.

Colin, is all your scale hard and stubbornly attached to surfaces or do you have bunch of loose gritty sludge stuff too?

Started work cleaning the stainless steal from panels. Whats the best way to bring some life back to those? I'd like 'em to be a little shinier... they're a lightly brushed / satin finish stainless steel and although fairly unmarked have lost they're lustre... as the S27 was a commercial catering machine I doubt they we're every that sparkly to begin with....

'till tomorrow

Stef


----------



## coffeechops (Dec 23, 2013)

tictok said:


> Colin, is all your scale hard and stubbornly attached to surfaces or do you have bunch of loose gritty sludge stuff too?


Bit of both to be honest - the stuff in the boiler mostly grey-brown flakes, but the HX was gritty, some in clumps, some solid, some attached, some loose like sand. Looked very similar to yours in colour and the loose stuff in texture.

Colin


----------



## tictok (Dec 1, 2013)

Time for a quick update:

All bits now clean and sparkly. Considering what to do with wiring loom. Re-use old one, or makes a new one?

It all worked okay, but some of plastic spade covers are a bit brittle and wiring braid is a bit discoloured....

A little worried I might have trashed the flowmeter thingymagic (see pic).

What's hidden underneath the resin / epoxy part? (the bit the 3 contacts disappear into.)

That whole section swivels quite easily... worried I might have broken some contacts inside? They're expensive to replace... :/

On the upside, there's no scale inside and the impella in the bottom part moves freely.

I guess I'll find out if it works or not when everything goes back together.


----------



## tictok (Dec 1, 2013)

Reet then, tonights mission:

I have to wait another day or so before bolting things back onto the frame / chassis. I'm pleased with how it's come out, but the paint needs to cure / harden a little more first. must be patient.... must be patient....

It's looking a damn sight better than the rusty, peeling thing it used to be:










Pleased with how the boiler and heat exchanger came out. No scale in sight. Not bad for something that's pushing 20 years old. I know it will be tarnished within 5 mins of use, but it makes me happy!










As I can't bold anything back onto the frame yet, tonights mission will be to put the boiler back together.

I've a whole set of new gaskets and bits and bobs - really must thank *espressotechno* for helping me out with those. Top bloke. Really helpful, really quick, and good price too. thanks!


















That will then leave rummaging through my 2 boxes of bits, fitting the remaining copper and brass back onto the frame tomorrow and then figuring out wether to reuse the old cabling or not whilst been very careful with the ageing and now very expensive electronics.. I think a replacement 'brain' gets close to a $1000 these days.


----------



## tictok (Dec 1, 2013)

Found a schematics for boiler, group and pipes.

Should help me remember what goes where, what needs washers and gaskets, what doesn't...

Added PDF sto manuals section of site in Coffee Wiki

Here


----------



## tictok (Dec 1, 2013)

By end of play last night I pretty much had boiler back together and group head, 3-way valve and solenoid sorted.

Tomorrow I start piecing everything else together...









//edit: Things seem to be getting a little out of sync... before this one, I posted a bunch of updates over the past couple of days which haven;t appeared yet. They were mainly of fresh shiny copper - the results of a few days cleaning.

Hopefully will appear when moderated, but well aware mods have been kept busy with site hacks etc.


----------



## tictok (Dec 1, 2013)

One week in and tonight was my original deadline for the refurb. It was a little unrealistic though and knew all along I'd never achieve it. The reate I'm going I know reckon I'll be pouring espresso by friday...

Anyhow, it's finally getting back on it's feet again (literally) and now the paint has hardened enough I'm adding a few bits and bobs back onto the chassis.

Trying to work from the bottom up, or adding the bits that would be a pain in the ass to fit in when it's a little more cramped. Just had to add the group head now though so at least it's kind of got it's identity back.

I'm actually really enjoying this part - my kind of jigsaw!

I'm finding it fairly easy to figure rout what goes where. The hard part is finding the right screw, washer, nut 'n bolt etc...


----------



## Daren (Jan 16, 2012)

I'm loving this thread! Impressive work - more more more please!


----------



## tictok (Dec 1, 2013)

hehe - thanks.

Just hope it all works afterwards!


----------



## tictok (Dec 1, 2013)

..post removed. Duplicate pics.


----------



## Jonathan007 (Aug 15, 2012)

Great watching this thread, really interesting!


----------



## iroko (Nov 9, 2012)

Thanks for more pics, great work


----------



## coffeechops (Dec 23, 2013)

Great stuff, love it when it starts to go back together - you're keeping me motivated!









What paint and process did you use?

Colin


----------



## tictok (Dec 1, 2013)

Hiya Colin - thanks again

For the frame / chasis I just attached it with a rotary wire brush on the end of my drill, followed by a lot of elbow grease with either wire wool or sand fine grit sand paper. I used hammerite straight to rust & metal. Previously I've always been too impatient with spray-painting, so took my time - just one or two very light coats each night over the course of 5 or 6 days, then about another 2 or 3 days on top of that to let it harden sufficiently.

For the steel side panels, I used a chemical paint stripper - real nasty stuff. Then loads of wire wool work. Then primed them. really boring work. I've still got a whole load more work to do on those. Not entirely sure what colour they'll end up yet.

Should I stick to original and retro Rancilio rocket red, ro do something different?

I was toying with the idea of powder coating them... don't have the spare cash right now though.


----------



## tictok (Dec 1, 2013)

A couple more updates overdue. Haven't managed to post until now.. life got in the way, then another forum outage again but will take my chance now!

So, a few more bits going in. Decided to tackle the wiring now too before it gets too cramped in there.

If everything works at then end I will probably remake the wiring loom with fresh wires and connectors...

















I couple of bits to tighten, new gasket in place and the boiler is then ready to go in.

Hardly recognisable as the same boiler I took out originally.









Painted this bit too. This was a right old rusty mess before I had my way with it.









Boiler in! Now it's got it's heart and soul back.

Getting there... Thats about as far as I managed to get that night.

SO glad I took lots of pics and labeled the wiring loom - it's made putting it back together sooo much easier


----------



## tictok (Dec 1, 2013)

Last night...

A few more bits n bobs bolted on, everything tightened, buttons and switches added.

Just about ready to test.









Temp reservoir









Power her up....

It's alive - a very welcome site!! Phew!









Uh-oh. The aftermath of a major leak.

Water squirted out of flowmeter at pressure. Household RCD trips, lights go out...


----------



## Daren (Jan 16, 2012)

More, more, more!!!


----------



## tictok (Dec 1, 2013)

Luckily Flow-meter just needed connections tightening. The two bolts are very close to each other, and stop each other turning if not done in sequence...

Dry things up. Check earth connections etc.

Time to test a second time.

Standing well back I nervously turn machine back on...

No leak from flow-meter this time.

Allow machine to get up to temperature and pressure. All the controls appear to work.









Unfortunately as soon as I reached temp water started dripping out of bottom of pressurestat and the join between boiler and group head. Nothing scary, just a solid and steady drip from both.

The drip from pressure-stat hits live wires (pressurestat is just above main wiring block). This time I have an RCD on an extension cable between espresso machine and mains - that trips, but at least all the lights in the house stay on.

That's about all I could take last night... it was nearly 1am too.

Not a complete disaster (at least the thing powered up and was responsive), but not quite as smooth as I hoped.

I tidy up and move machine out of way... looks what I find underneath!!









hmm... I've replaced all rubber o-rings, gaskets etc with new.... I wonder if that's the one from grouphead / boiler joint... perhaps it somehow fell out when puttung the pieces back together.

Go to bed hoping the grouphead leak is an easy-a--fix as popping the o-ring back in...


----------



## tictok (Dec 1, 2013)

SO, tonight...

I manage to remove pressurestat, take apart again, clean again, add a little teflon tape, put back together, bolt back on to chassis and reconnect.

Fingers crossed.

Manage somehow to split boiler and grouphead without having to undo and remove everything. I've got a bunch of stuff wedged underneath the boiler to hopefully stop in dropping.

It's drops a bit... will be a royal pain in the ass to get back into the right position so holes line up etc. C'est la vie.

Good news though! The o-ring I found under the machine last night does appear to be a missing o-ring from group head / boiler joint, so I clean up boiler and group head faces again, pop the o-rign back in it's place and spend the next 30 mins banging my knuckles and swearing every 2 mins until I manage to get everything back together and tight.

Cross fingers again....


----------



## Daren (Jan 16, 2012)

What did you do with the side panels in the end?


----------



## tictok (Dec 1, 2013)

So, give kids a quick bath, pack'em off to bed, and come back down to test for a third time...

All ready to turn back on.

I currently couldn't be happier.

Machine has now been on, at pressure for past 2.5 hours with no leaks!!!!!!!!!!!!

Everything appears to work, even the flow-meter that I thought I'd knackered.

Pressurestat needed a little tweaking to get an acceptable pressure, but I can hear it click away every now and then as it should, and pressure is remaining stable.

Feeling very smug, lucky, proud, relieved and happy all at same time.

I might be drinking espresso before the weekend afterall!

Stable boiler pressure after tweaking pressurestat

















No leaks.... anywhere!

Looking good!

















Only thing I'm wondering is that there's an occasional drip or his from safety valve / pressure release tube into drip tray area.

Tube seen in middle of pic above.

Can't remember if this is normal?

Boiler isn't over pressure, so should I adjust safety valve on top of boiler if it's at all possible?? I have no idea?

Does it need replacing with new one, or should I just leave it? It's the tiniest hiss out of the tube every 20 seconds or so, and a couple of drips per minute...

Next up, I'm going to let machine cool down, and start putting on front panels, and the freshly painted mesh from the lower-front and underside.

I'm going to leave top and side panels off for a few days to keep eye on things.

Overall though I'm very, VERY, HAPPY!


----------



## Dylan (Dec 5, 2011)

Amazing mate, she's a beaut, like you raised her yourself


----------



## tictok (Dec 1, 2013)

Hiya.. thanks!

It's been an emotional night - lol!

To answer your question Daren, I still haven't decided what to do with side panels.

They're primed, but need more work.

What do you guys think I should do? original red?


----------



## Daren (Jan 16, 2012)

I'd pimp it... Make it an original one off (tastefully). Are the panels flat or textured? Have you considered a metallic?


----------



## jeebsy (May 5, 2013)

Get it pimped!


----------



## coffeechops (Dec 23, 2013)

Another vote for pimping! Sparkle gold and red I reckon...


----------



## espressotechno (Apr 11, 2011)

Just noticed the steam pressure is highish @ 1.3/1.4 bar. Reducing it to 1.0 bar may stop the safety valve from hissing, as well as reducing the boiler / group head temp. a little.

It's not advisable to adjust the boiler safety valve - better to buy a certified new one. But first try tapping it firmly with a lump of wood.....


----------



## tictok (Dec 1, 2013)

Hi y'all

So pimping it is. That bit will have to wait until after I've moved house in a couple of weeks but gives me plenty of time to come up with a good plan. It's won't be anything too glam though... gotta be stylish, not tacky!

I've been running that machine without side panels for a fews days and apart from the hissy safety valve I'm happy.

I've already tweaked the pressure stat to get boiler pressure down to around 1.2 bar.... will give it another twist tonight and see how close to 1 bar I can get it.

Group head is running a little hot / steamy... having to flush out the water dance each and every time, so reducing boiler temp / pressure will hopefully help.

Yep, probably not best to tamper too much with the safety valve.... don't want my boiler going 'BOOM' in mtg face!

Also, what's the best way to reduce group head pressure? Adjusting either the pump pressure or adjusting the OPV?

Thanks!


----------



## iroko (Nov 9, 2012)

Great work, don't you just hate it when you have an o ring or screw left over when working on something like this, but it's all good experience for

next time.


----------



## espressotechno (Apr 11, 2011)

Reducing the steam pressure reduces the boiler temperature...which reduces the group head temperature (the boiler water heats the water in the HX tube, which then heats the group head).

The steam pressure is controlled by the pressure switch (the grey box ). On the grey Sirai pressure switch, turning the screw clockwise reduces the pressure. Standard pressure for a commercial machine is 1.0 bar.

The pump pressure doesn't effect the boiler temperature. Too high a pump pressure, usually around 12 bar, will pop the OPV. I think your m/c doesn't have a pump pressure gauge.....so you'd have to borrow a pressure gauge assembly which screws onto your portafilter.


----------



## tictok (Dec 1, 2013)

Hi espressotechno - thanks for the info!

Tweaked the pressure switch (or pressure-stat as I've been calling it - probably incorrectly) further. Won't be heating up again until the morning, but will hopefully now be on 1-bar or there abouts - easy to tweak further as needed though.

Yeah, realise pump pressure shouldn't effect boiler temp, but ever since I swapped out the pump a while ago I've suspected a little too much pressure / flow speed at group head. So reading into your post, would it be best to tweak pump flow speed / pressure and leave OPV alone (although I've already opening it up a bit)?

You're right, there's no pump pressure gauge, but I'm only a 3/8" female to female connector away from making my own portafilter pressure gauge from bits I found in the garage


----------

