I read a few other threads about the Tunze 3155 sensor failing. Mine is 3-4 years old and will no longer fill, if I power off the controller and turn it back on it fills for 20 seconds. If I raise the float switch I get the overfill alarm. I cleaned the sensor and have the same issue. I took it out of service for now as I'm doing a tank swap, but I'd love to get my old reliable Tunze a new sensor for the new tank.