I have a couple 305's and a few sensors mounted to different bikes. One of the Cadence Sensor has stopped working. I've replaced the battery and even swapped it with one that is working and it still won't work. Even cleaned the contact points in the battery compartment. When I press the reset button the red light will come on but it's very dim. Once the magnet passes the cadence it also comes on but once again its dim. It doesn't appear that it comes on when the magnet passes the speed sensor. I noticed with the sensors I have that do work make a tick when the magnet passes the sensors. This one is making a tick sound but it's faint. I've also used different magnets. Could it be the magnet in the sensor had become discharged? Is there anything that can be done to fix this?