Siemens TK68E571 no longer delivers coffee

Hello,
I need your help please. We do not know what to do. We have a Siemens TK68E571 and have replaced almost everything by now: brewing unit, brewing unit drive, flow pump, hoses and still we get no coffee at all. The machine reports all items: Device rinses, device heats, small coffee, press coffee, then makes you briefly something, then comes system fill and then again directly on small coffee. The water runs directly into the drain pan. Somehow I have the feeling that the water does not run into the brewing unit. Despite new drive (incl.Drainage valve). We have even 2x the drive and the brewing unit now replaced. We are in despair. Can someone help us?

Then something else. We have also replaced the ceramic valve for safety. However, with the new ceramic valve you could not switch to water supply. Here also the same problem no coffee but in addition still no switching possibility on water. Now we have the old ceramic valve again and have steam and hot water. Just no coffee.

Does anyone have an idea? They are all original parts. But with the current parts, the dealers always say "has been replaced with....".

Many thanks Heike