Door stops mid-travel and will not complete open or close cycle; control board LED blinks 8 times repeatedly.

Safety first: Disconnect power before removing covers. Ensure the door is stable and cannot fall.

• Reset travel limits: Follow the Mighty Mule instructions to clear and reprogram open/close travel. This often involves holding the SET or PROGRAM button until LEDs flash, then running a full open and close cycle.
• Inspect drive components: Remove the opener cover. Check the motor shaft encoder wheel (if visible), drive sprocket, and belt/chain for looseness or damage. Tighten set screws and tension the belt/chain per the manual.
• Check for obstructions: Verify the door moves freely by hand through full travel. Correct any binding before reattempting calibration.
• Power stability: Avoid interrupting power during the calibration cycle. Use a stable circuit without frequent trips.
• Replace sensor or board: If calibration fails repeatedly and mechanical parts are sound, the motor encoder or control board may be defective and require replacement.