Chamberlain Disengaged Trolley or Broken Drive Connection

Garage door will not open; opener runs but 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

Emergency release rope pulled, Broken trolley, Stripped drive sprocket, Broken belt or chain

How to Fix / Troubleshooting

Safety first: Ensure the door is fully closed or securely propped before re-engaging the opener to prevent sudden movement.

Steps to fix:

  • Check emergency release: Look at the trolley on the rail. If it is in the disengaged position, pull the red release handle toward the opener or door (depending on model) to re-engage.
  • Inspect belt/chain: Verify the belt or chain is intact and moving when the opener runs. If broken, replace with a Chamberlain-compatible belt or chain kit.
  • Check trolley: Inspect the trolley for cracks or missing pieces. Replace the trolley assembly if damaged.
  • Inspect drive sprocket: On chain drive models, check the top sprocket for stripped teeth or wobble. Replace the sprocket and gear kit if worn.
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Repair Difficulty

Medium 3/5

Required Part

Trolley Assembly / Belt or Chain
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