The control pad red light above the button that is pushed comes on.

I will be checking the wiring. Wife is catering this week, the van is not starting, and I've been fighting the flu, so broken espresso machines are forced to take a back seat

Wow, all at once... Get better soon!
By the same logic, a good jackpot must be due your way soon too
Sure, resolving these puzzles is just a matter of time.

Progress, a little.

I removed the panel behind the groups, which exposed the electronics board and revealed a blown fuse. Replaced fuse, hit left group manual brew button. Pump kicks on and water comes out of the group screen. And everywhere else. It's positively spraying from multiple leaks.

So I start tracking down leaks. The right group flowmeter is spraying water all over. Take it apart, the thin rubber o-ring seems not seated correctly, re-fit the o-ring, spend 10 minutes looking for a dropped screw, get the flowmeter back together, its not leaking.

The check valve leading back to the pump is leaking badly. Tighten that, no more leak.

The pump itself is leaking, not a lot but too much to ignore. This is a Procon type rotary pump. The leak is from the "face", the round plate where you normally find the manufacturer's sticker. At least that's where I feel water leaking. Because I can't see it.

This machine isn't built like my Elektras. Those are a frame on which parts are hung. The outer panels are merely cosmetic. Remove them and you have full access to everything.

On this Grindmaster, the machine is a stainless steel box with an internal partition between the top part when the pump, lines, flowmeters, boiler end plate, fittings are, and the lower part where the electronics and boiler body are. The top part is surrounded by the walls of the box. So anything near the edge of the top part, like the pump, is obstructed by the walls, and worse yet the walls have an inward lip that obstructs stuff even more. And in general it is hard to get a wrench on many fittings. It seems like you're supposed to own a set of crowsfoot wrenches. Inch, not metric. I barely own any inch wrenches!

Anyway, the pump will need to be removed and rebuilt or replaced or something. But anyway I carry on testing.

The right group has a problem. When I push the buttons, the pump runs but no water comes out. I remove the solenoid, put a screwdriver shaft through it, push button, I can feel something vibrating or tugging on the screwdriver. So the solenoid is not totally dead. I turn the machine on (I'm being cautious and turning it off when touching anything electrical) to push the button again and...the GFCI outlet trips. Reset outlet, turn machine on...trip.

I look at the machine's lower part. This machine is so well designed that water leaks in the upper part can apparently get the electronics board wet.

So, eff this. I blow compressed air around and I'm going to let it dry overnight before screwing with this again.

If I haven't made myself clear, I dislike the way this thing is built. It's not easy to service.

But I do think I'm making some progress.

Interesting thread! Keep us posted!

Machine dried off and no tripping of the GFCI.

So I need to figure out what to do. The dance company can't afford anything much. They are trying to get a grinder and their budget is $200. So they can't afford to buy a bunch of parts for this. At least not until they have it running and determine if will actually make them a little money. I'm willing to put $100 into it for them but not more. I actually have a spare Procon pump I'd give them but it's not exactly the right one.

What I'm thinking about is:
- Rig up a drain tray for the pump and a drain line, so that it can seep away without harm.
- Try to get the right group working without spending any (of their) money. Keep investigating solenoid, remove valve, see if there is something going on there that can be fixed with cleaning. I'll buy them a valve if needed. There's no sign of scale by the way, and the line from HX to valve is not obstructed, I loosened its fitting at the valve and water was coming out under pressure when the brew button was pressed and the pump running.
- Worst case, they get a machine with one group working and full steam/hot water function. I don't see them doing enough volume to require two groups.

Then they can use it, see if they can make money (selling lattes during performances etc), if yes then have it repaired fully.

Maybe I'm just being lazy.

Great to see your progress!

To test your solenoid hypothesis, maybe you could swap it to the one known to feed the other group.
Perhaps it's just some other blockage down the line

Does the pump leak even when not under load?

I swapped the solenoid from the working left group to the non working right group. The right group still doesn't work.

So I'm suspicious of the right group valve itself. I will figure out how to remove it - access is poor.

I guess the group itself could be clogged but that seems unlikely.

The pump face does not leak when the pump is not running, it seeps when the pump is running - like a few drops in 30 seconds. There is another, smaller, leak at one of the fittings leaving the pump outlet.

I tried pulling a shot with the working left group. The espresso was more like an Americano. The group head gasket is so dry and rock hard that it isn't sealing and water overflows the portafilter and pours into the cup Ordered a pair of gaskets.

What did this machine do in its past life to deserve this kind of love?

Thanks for sharing your work!

Thank you! I didn't read that part of the manual, so I will definitely check that.

Tried steaming (used water + dish soap). The steam wand tip orifices were partly clogged up and so was the drain hose. Easily fixed but no-one had bothered.

It is interesting because the machine is not dirty, well-used, or dinged up at all, but it has so many problems. I am guessing that it was in some light duty situation, developed a problem, and then another and another, no one bothered to fix anything, and finally stuck the machine in storage for many years.

I am starting to understand why unrestored old commercial espresso machines can often be bought for relatively little