Garmin Edge 305 not registering cadence. Timer...

My Garmin Edge 305 won't register cadence at all and goes into autopause mode while pedaling. I have checked both magnets, and they are registering on the GSC 10 sensor. My timer starts and then stops after a few seconds. It then starts and stops randomly, but mostly stays in the "autopause" position. I have reset the sensor, and, again, confirmed that it is picking up both the crank and spoke magnets. Help !!