Krups EA 8250

Hello, everybody,

I haven't been here for a long time, but now my EA 8250 has come up with a new problem and I'm not sure what to do despite reading many articles.
During the flushing process, the piston shuts down as usual and everything runs smoothly. However, if I want to make myself a coffee, then the piston does not drive down completely. The upper
seal ring is visible. The coffee is brewed and partly runs out at the top. The pomace gets stuck in it and is only thrown out with the subsequent autotest, is rather dry. With every forum post I read, I change my mind about what it might be: Flowmeter, drainage valve or hydraulic cylinder?
I
don't know.
I
'd be very grateful
for your help
.
Many greetingsCorinna