My Craftsman Garage door has been working fine (model 139.53681B or 139.53686) until recently. When I hit the button on the wall, I just hear a CLICKING sound but the door does not open and the lightbulb connected to the motor unit does not go on. I unplugged the unit for 15 minutes and it seemed to work again, but the problem comes back.

I wonder if anyone encountered this type of a problem.

I've checked the sensors, they seem clean and un-obstructed.