Does It come on when the bin gets fullIJ I had that problem and found the the bin loader was causing the drive shaft to move over and the lock collar moved with the shaft. Who ever put the bearings on the drive shaft, they didn't lock the collars to the bearings they loctited them to the shaft. When the bin emptied the drive chain pulled the shaft back in line. You are correct about the sensor being a pain to get at . Good luck Bert