The plastic gears were completely stripped out and would not lift the door any longer. I ordered the replacement gears and changed out the main gear and the worm gear . When the opener would only move a few inches and stop I tried running the motor with no load attached and the limiting switches taken out of the circuit but the motor still will only run a few seconds and then emit a clicking sound. My next step will be to remove the gear and see if the motor will run without the worm gear contacting the main gear. I'm still puzzled about the clicking sound when the motor stops running.