Jura Impressa F 70 endless loop

Our Jura Impressa F70 has the following problem:

When switching on "tap open" appears  after turning on the tap then "system feels", after a time "tap closed", but then nothing happens, all this in an endless loop.

You don't hear the typical humming of the pump

>So far the following has been done:

1. Brewing group completely removed / cleaned, including drainage valve cleaned and replaced

2. Drain valve replaced

3. flowmeter disassembled / cleaned, hoses cleaned / correctly reinstalled (lower hose to water reservoir, upper hose to pump)

Does anyone have any idea how best to proceed?

First find out if water is flowing out somewhere or not...

What is a "typical humming" of the pump? Is it humming at all, whether typical or untypical?

Zu 3. The flow direction is marked with arrows on the flowmeter.

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Pessimist: Ganz schön dunkel hier...
Optimist: Ich seh ein Licht am Ende des Tunnels...
Realist: Mist, da kommt ein Zug...
Zugführer: Was machen die 3 Deppen auf den Gleisen?

hello! were you able to solve the problem? we have exactly the same problem!
lg a friend