How to Loosen the Chain on a Garage Door Opener

Close the garage door, and activate its safety latch. Many garage doors use a sliding safety latch that locks against the garage door's roller track, the C-shaped track found on each side of the garage door.

Set up a ladder under the garage door opener's trolley, located on the chain rail. The trolley consists of two parts: the inner trolley and outer trolley. The door opener's chain connects to the inner trolley. The garage door's activation lever and the emergency release lever attach to the outer trolley.

Pull down on the trolley's emergency release lever, separating the inner and outer trolleys. This releases the tension on the chain.

Place the correct size wrench on the inner trolley's inner nut, the lock nut located on the threaded rod between the trolley's adjustment bracket and the chain. Place a second wrench on the inner trolley's outer nut, the nut located between the trolley's adjustment bracket and the end of the threaded rod. The threaded rod adjusts the tension on the chain.

Hold the inner trolley's outer nut still, using its wrench for leverage. Turn the inner trolley's inner nut counterclockwise until it spins freely, using the inner nut's wrench for leverage.

Turn the inner trolley's outer nut counterclockwise with its wrench, loosening the garage door opener's chain. Continue to turn the outer nut counterclockwise until the center of the chain starts to sag.

Spin the inner trolley's inner nut clockwise until it touches the inner trolley's adjustment bracket, using a hand to spin the nut. Hold the inner trolley's outer nut still, using its wrench for leverage. Lock the inner trolley's inner nut against the adjustment bracket, using the correct wrench to turn the inner nut clockwise one full turn.

Slide the outer trolley over the inner trolley, and deactivate the emergency release lever.