LiftMaster
Stripped Drive Gear or Disengaged Trolley
Garage door opener motor runs but the door does not move; trolley stays still.
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Safety Warning
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.
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Possible Causes
Worn plastic drive gear, broken sprocket, trolley in manual release position, stripped belt/chain drive
How to Fix / Troubleshooting
Safety: Disconnect power and ensure the door is in the down position before servicing.
- Check emergency release: Ensure the trolley is re-engaged. Pull the red release cord toward the opener, then run the opener to re-latch.
- Observe operation: With the cover on, run the opener and watch the chain/belt. If it moves but the door does not, the trolley may be disengaged or stripped.
- Inspect gear and sprocket: Remove the cover and inspect the main drive gear and sprocket for missing teeth or plastic shavings.
- Replace gear kit: Install a LiftMaster gear and sprocket kit if the gear is stripped. Follow kit instructions carefully.
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Repair Difficulty
Hard
4/5
Required Part
Gear and Sprocket Assembly
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