Garage door opener motor runs but the door does not move; you may hear the chain or belt moving while the door stays closed.

Safety first: Unplug the opener and pull the emergency release to disconnect the door. Do not operate the opener with a disconnected or jammed door.

• Inspect drive sprocket: Remove the opener cover and look at the top sprocket where the chain or belt attaches. If it wobbles, is broken, or covered in white plastic shavings, the gear is stripped.
• Check door balance: Before replacing parts, lift the door manually to ensure it moves freely. A heavy or binding door will quickly destroy new gears.
• Replace gear and sprocket kit: Craftsman offers a gear and sprocket replacement kit. Remove the chain/belt, disassemble the opener head per the instructions, and install the new nylon gear, shaft, and bushings.
• Re-tension chain/belt: Reattach the chain or belt and adjust tension so there is about 1/4 inch of sag at the midpoint for chain drives, or slight deflection for belt drives.
• Test operation: Reconnect power, re-engage the door, and run a full open/close cycle while observing for smooth movement and proper stopping points.