Problem with "Water tank empty" on Jura 300

Hello. Before a month a go, on my Jura impressa 300, it's activate signal "Water tank is empty", but It's full of watter.
I checked everythings , but I didn't found any mistakes.
This model don't have magnetic sensor for water level control of water tank.
How control electronic device get signal "Water tank is empty"?
I checked water hoses, and everything seems OK (neither of these aren't clogged).
On initial turn on of machine, the water flows thru the every hoses, then stop and it's shows signal "Water tank is empty".

Does anybody have electrical shema for this model?

Please, help !!!

Probably through the flowmeter.
Do you have lime? If so, rinse with descaler. Otherwise disassemble and clean the flowmeter.

Open the flowmeter and clean it, I think the wheel in there is blocked.
The flowmeter is a white round part with two hoses, which sits between tanknund pump.
The hoses can be left on, because to open it you only need a small turn to open it upwards.