How to Fix / Troubleshooting

Safety first: Unplug the opener. Do not continue to run a humming motor; it can overheat. Springs are dangerous—do not adjust them yourself.

Disconnect door: Pull the emergency release and move the door by hand to ensure it is not jammed or excessively heavy.
Inspect chain/belt: Look at the rail. If the motor runs but the chain/belt does not move, the internal drive gear is likely stripped.
Open the opener housing: Remove the Guardian opener cover. Inspect the nylon or plastic main drive gear and worm gear for missing teeth or plastic shavings.
Replace gear kit: Install a Guardian-compatible drive gear and sprocket kit, following the service manual. Grease gears lightly with manufacturer-approved lubricant.
Reassemble and test: Reinstall the cover, reconnect power, and test operation with the door re-engaged. Re-set travel limits if necessary.

Garage door opener hums but door does not move, Guardian unit light comes on but no lifting action.

Possible Causes