Thank you all for your tips.
I did try do remove the paddle wheel steel axis in order to remove it from the plastic housing, to clean and and check the wire, but no way. Using a small screw driver and forcing the axis on one of the sides, did not work. The manual refers a specific wheel position (a more flat paddle way down), but apparently all the four paddles are equal!
The manual also refers to a special tool to remove more easly the axis, delivered with a ...
new sensor+cable (200 + Euros)
So, I will try to follow Roline and Timebandit suggestions.
Thank you all,
Alf,