Craftsman 1/2 hp GDO won't move more than 4 inches
The model# is 139.535006 (no sensors, really old) and the issue started when the door would only move up and then down 4 inches, then stop. Now the motor just "clicks" and the door wont move at all. I can screw the motor shaft by hand (chain is off) to the middle of its cycle and occasionally the gear will turn until it reaches the top or bottom. Once it hits the top (or bottom) limiter it will do nothing if pressed again...the motor just clicks or only moves a fraction of an inch. I have swapped both rpm sensor board and logic board with my other working unit to no avail. BTW I replaced the worm gear/sprocket years ago and it has been fine. I think what may have started all this is me shutting the door on a bucket and the door reversing itself???