You must have flow to adjust a pressure gauge in the filter, otherwise the static pressure will be the same as the pre-gicleur pressure.

Even a Scace or home-brew portafilter device is an approximation. If you want to know, you need to measure during an acutual shot. See Digital Pressure Adapter

I was suspecting this, I guess I should have the e61 pressure gauge instead. Currently I am monitoring brewtemp, but I guess I have to switch between these.

I've never put the group pressure adapter back in. About 8¼ bar suits me just fine.

So, erm...
It's the spring first, then the brass+Rubber seat, with the small rubberpart pointing towards the spring, right?

Awesome exposition of the issue by those responding! Learned a lot by reading cafeIKE, GC7, and Nate42's comments about yet another incredible IZZO machine! Fantastic pictures, details and info by AndersHP really awesome

. . . while you are in there, and have everything open, you might have a great opportunity to inspect your "non-return" valve ("FE 303" in the diagram provided earlier links to) as part of this great thorough checkup of the entire line from your pump through your HX-Line Thermosiphon loop and associated OPV assembly. Might be fun and interesting to see if there are any mineral buildups or any other obstructions in the non-return valve ("FE 303") that might interfere with overall pressure provided by the pump.


As cafeIKE mentioned worth considering all the affected components including thermistor on pump. . .

Thanks

I wish I would but the one-way valve is really hard to get to. I think it would require total disassembly of boiler including pipes to and from it.
I'm thinking this project needs to be closed before I do more damage than I can fix.

I cannot find the mentioned thermistor, the wires for the pump just look like wires. Is this a problem?
(see bottom photo on page 1 for a glance at the wiring). What does the thermistor do, exactly? Could it be placed somewhere longer down the wiring?

So, a little status update here.
Got everything reassembled, bought a Coffee Sensor manometer for the brewhead and adjusted the OPV to 9 bars blindfiltered.





The new pump runs fine, had guests yesterday pulling 7 shots in a row, and it didn't seem to act up like it used to. So problem solved. Thanks for the help, everybody!