How to Fix a Cuckoo Clock's Pendulum to Run

Watch the pendulum for movement before you inspect and repair any mechanical parts. Adjust a pendulum that swings too slow or too fast by moving the pendulum slide up and down. Move the slide up to make the pendulum swing faster and move it downward for a slower swing.

Inspect the weights on the cuckoo clock for any obstructions. These weights must fall beneath the clock without touching anything, including resting against the wall or touching other items attached to the wall, because this prevents gravity from fully working on the weights, which forces the pendulum to swing slowly. Remove all obstructions.

Pull on the weights if the pendulum does not swing at all. This indicates a possible detachment between the weight's chains and the inner sprockets. The chain has detached if the weight does not move when you pull with moderate force.

Remove the back of the cuckoo clock to expose the inner sprockets. Grab the chain and wrap it around the sprockets attached to the pendulum's mechanics. Close the back of the cuckoo clock and test to see if the pendulum runs properly.