I agree with Nate42 and the "Without Portafilter pretty well proves it.

Your OPV is dumping most of your flow, even at almost unmeasurably low pressure. Clean/Fix/descale/examine the OPV, it shouldn't be passing more than a drop or two with the brew valve wide open and nothing in the brewhead. If the rubbery valve-face in the OPV is hard or mis-shapen, you can replace just the valve-face, clean the brass body and probably solve the problem.

It may be possible that that flow is going over your priming valve (The bubbler valve on the pump outlet), but that much flow passing through that tiny, plugged outlet with the brewhead wide open strikes me as nearly impossible. I'd have to see it to believe it.

If the OPV was dumping water at low flow, how could it maintain 10 bar with a blind basket? I've read, although not seen any specs, that the priming valve (bubbler) remains open until around 6-8 bar, so if the group is run open, it probably is responsible for dumping water back to the reservoir. My Andreja shows the same amount of outflow to the reservoir with an open group and I have no issues with my machine. Maybe I'm missing something?

EDIT: Shot a video of my Andreja with open group. Embed link doesn't seem to work so link is to Vimeo

http://www.vimeo.com/499780804

nahau wrote: I've read, although not seen any specs, that the priming valve (bubbler) remains open until around 6-8 bar, so if the group is run open, it probably is responsible for dumping water back to the reservoir.

That's intriguing. Is the priming valve something that I can service?

nahau wrote:My Andreja shows the same amount of outflow to the reservoir with an open group and I have no issues with my machine. Maybe I'm missing something?
Shot a video of my Andreja with open group.

OK, so maybe the outflow is a red herring.

Before I read your post I took apart the OPV, descaled and reassembled. There was some scale. The valve seat seemed like it had a lot of lube on it. When I reassembled I didn't lube it, I only put 111 on the o-ring. I'll set the OPV to ~10bar in the morning with the blind portafilter and see if anything changes during brewing.

These pics are before cleaning:

I've never had to service a priming valve and never had the need to replace one either. I believe its a one way valve, and you'd be hard pressed to find serviceable parts for it. Not only that, but different vendors appear to make this valve so getting the "right" parts might be a cr*p shoot. Better to just clean it if need be, or buy a new one if the time comes.

It might just be the photo being out of focus or water droplets (or lube?) on the bottom seat where the main pressure seal seats, but the brass looks "pitted" around the edges. OPV's don't last forever so if it is pitting, then you'll have to replace the OPV eventually. How's the pressure seal (green)? Does it look overly compressed, damaged, or maybe hardened (as John mentioned)?

You're looking at all the right stuff, so you'll nail the culprit soon for sure.

I had a nearly identical issue with my Isomac Millennium. At first I adjusted the OPV to bring the pressure up. The pressure continued to drop. I just replaced the pump. Voila! Now the pressure is too high and I have to adjust the OPV again the bring the pressure down to where it belongs. Always fiddling! In any case, it was the pump. Maybe you are seeing the same thing.

After cleaning and readjusting the OPV it didn't make a difference to brew pressures. The valve seat does look tired, but it really didn't feel like that was the source so I went back to being suspicious of the Vario grinder.

I tore it down and readjusted everything tonight using the 'Alicorn'/''FortArio' threads. Now I can start to get reasonable pressure again with finer grind settings. I've ordered a bunch of new parts from Baratza to upgrade the Vario so I'm optimistic the grind settings will be more stable after I get them in.

If any of you are Vario/Forte owners, what Macro/Micro arm settings do you end up at for your brewing? After readjusting everything it's back to the recommended "burrs just start touching at 2Q" calibration setting. I got about 8 bars tonight at 2E. I'll try finer in the morning...

I've still got to look at the group to figure out the brew valve/pump timing problem mentioned earlier in the thread. Hopefully this weekend. I can see a big parts order in my future.

Thanks for all the input so far!

Per @JRising's suggestion I opened up the top of the group to look at the brew valve and cam.

It looks like there's some wear on both surfaces but I don't know if it's enough to cause problems. I'll assume it is and order parts. The cam could be original from 2004. I haven't replaced it since I got the machine.

Poor quality pics attached.

I did some upgrades to my grinder and was keen to see if I could get anywhere with the Andreja pressure problem before new parts arrive.

So, today I used nahau's exploded pump parts photo to tear it apart, descale it, 111 lube existing o-rings, and put it back together.
Then I took apart the priming valve and gave it a similar citric spa treatment.
As I was putting the priming valve back on the pump and congratulating myself for not losing any of the tiny parts the valve body's threads cracked off inside the pump.

Then there was cursing and a new plan.

I swapped the borked pump part with one from an old pump I replaced years ago and decided to try going without a priming valve.

Pretty dramatic change: Now it's hitting the OPV limit using the same 20g of beans at the same grinder setting that only got to ~4bars of pressure this morning.

Since I wasn't scientific I don't know if it was the pump cleaning or the priming valve bypass that solved the problem. Either way I'm hoping I'll finally be able to dial in a proper shot tomorrow.

Please let me know if I'm taking risks without that priming valve in place. The new one probably won't be here for a week or two.

The dialing fun lasted for about 4 shots this morning. I clicked up the grinder one more time and it seems I went too far.
The grind was too fine and the OPV was doing its thing for a few seconds of ristretto flow. Then the pump started humming and output stopped.

I don't know if it's lost its prime or if an overload protection has kicked in. I'll take it apart again tonight and see if I can figure anything out.

Aeropress coffee for the rest of the day...

Your previous post (#18) about the priming valve is a bit ambiguous. You say the valve body broke, and then you swapped the borked part in from an old pump. Did you swap in a priming valve, and if so, why are you running without it? Not sure I understand what you're trying to say.