Opener hums but door does not move; logic board LED flashes 4 times, pause, then 1 time (4-1).

Safety first: Unplug the opener. Do not continue to run a humming motor; it can overheat and cause damage or fire.

Steps to fix:

• Check door lock: Ensure any manual slide lock on the door is fully disengaged.
• Test door manually: Pull the emergency release and move the door by hand. If it is hard to move, have the door and springs serviced before working on the opener.
• Inspect drive gear: Remove the opener cover. Look for plastic shavings and inspect the main drive gear and worm gear. If teeth are worn or missing, replace the gear and sprocket kit.
• Check motor capacitor: Locate the start capacitor (usually a cylindrical component). If it is bulged, leaking, or cracked, replace it with a Chamberlain-specified capacitor of the same rating.
• Test motor shaft: With power off, try to rotate the motor shaft by hand (if accessible). If seized, the motor assembly must be replaced.
• Reassemble and test: After replacing faulty parts, reassemble the housing, restore power, and test operation.