You can see the sprocket from the top of the garage door motor has been knocked off. This would indicate that the drive sprocket has completed it’s cycle of life.

After the new gear assembly has been installed in the LiftMaster. You can see the fresh nylon plastic that is ready for it’s tour of duty.

View of the top of the garage door motor that has a new drive sprocket installed. This gear assembly is brand new and will drive the garage door for the new fear years. The reason why this part failed was most likely caused from a heavy wood garage door that just over stressed the gear over time.