Bosch VeroCafe Latte brewing unit constantly full

Hello everyone,

we have a 5 year old Bosch VeroCafe Latte. Always regularly decalcified and cleaned.

It has happened before that one could hear that the engine or something else has to exert itself as if something is stuck. After that came the message "Clean brewing unit" and it was full of coffee grounds. But now I constantly have the problem that there is always coffee powder in and around the brewing unit and the brewing unit makes these strange noises.

Question is, does anyone know the problem? Is it the brewing unit? Then I would either disassemble and clean them or get a new one.

I am technically experienced and have already disassembled some devices. I'd like to know your advice first.

Small addendum:

>I came to the service menu, it recognizes the position of the piston (whether below or above). So that doesn't seem to be the problem (microswitch)