LiftMaster Failed Motor Start Capacitor or Seized Motor

Garage door opener hums but does not move the door; motor may stop after a few seconds.

This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.

If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.

Possible Causes

Defective motor capacitor, seized motor bearings, jammed gear assembly, overloaded door

Safety: Unplug opener before opening the housing. Do not repeatedly run a humming motor.

Check door balance: Ensure the door moves freely by hand.
Inspect capacitor: Locate the motor capacitor (usually a cylindrical component). If it is bulging, cracked, or leaking, it should be replaced with the exact LiftMaster-specified part.
Check for jams: Inspect the gear and sprocket assembly for binding or broken parts.
Replace parts: Replace the capacitor first. If the motor still only hums, the motor assembly may need replacement.

Hard 4/5

Motor Capacitor

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