Ihave a 1988 Stanley dlux 1/3hp door opener that cracked the gear case where the worm gear engages the rest of the mechanism. I replaced the gear case and there is nothing that is binding or seized, but the motor does not turn the drive gears. When power is applied, the motor hums but it does not activate the drive. In the process of changing the gear case I had to change the adjustment mechanism behind the circuit board in between the gear case and the circuit board. I am wondering whether the up and down door mechanism is far enough out of adjustment to create my problem, or whether I should be looking for something else.
In the process of breaking down the mechanism did try to operate the door both up and down, which may have put it out of sequence. I would appreciate any ideas and information.

  • I'd start by isolating the motor. Remove any load from the motor (possibly by removing a gear or two, depending on the opener), and try to run it like that. If the motor spins, the problem may be that something is bound up. If the motor does not spin, it's likely time for a new motor.
    – Tester101
    Sep 15, 2015 at 13:59
  • Unless it's a fairly expensive model, door openers aren't usually worth spending too much time fixing (unless you just enjoy working on them). Sometimes it's better it to spend your time installing a new unit instead.
    – Tester101
    Sep 15, 2015 at 14:01

1 Answer 1


Many garage door openers use fractional horsepower PSC motors. These motors have a run capacitor that can get weak or go bad, reducing the motor's start and run torque below acceptable levels. This is a very common failure with single phase HVAC equipment, too.

On garage door openers I have repaired for friends and family, units that displayed the symptoms you describe had a bad run capacitor.

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