Melitta Coffee Solo&Milk

Hello in the roundI have the following problem
:The coffee is ground properly and falls dry and ground into the pomace container. The boiling
water runs into the collection tray. Work already done
:Brewing unit tried from another working coffee machine
= same resultDrainage valve
completely replaced with new sealing rings
= same result
Do you still have an idea?
I am at a loss?
I would be very happy about further tips!

I took the machine apart again
.

Seals checked, front panel removed. You can see that the hot water runs over the black hose in the front left into the collecting pan. The ground dry coffee powder still falls into the pomace container. But now I noticed that the driver in the inner ring has hardly any teeth left. There are normally 3 teeth there. These are hardly present with my carrier. Thus a
slight slippage
develops
.
Can it really only be because of that? Not that I order the driver now and more things are broken and I
have to
order spare parts again
.