Belt-Drive Opener Repair: what to note first

The door used to glide up with a soft hum. Now there is a sharp clack every second or so, and if you stand underneath you can see the belt sagging below the rail and slapping it on the way up.

Worth answering before the call

Does the motor run while the door stays still, or does the door stop partway? How wide is the door, and is it a single or a double? What is the belt doing: sagging, slapping, clicking, frayed, or hanging loose?

The motor runs but the door stays still. What has happened?

Something between the motor and the door has let go. On a belt drive the usual suspects are a broken clip where the belt joins the trolley, a belt that has jumped off the sprocket or idler pulley, a trolley that failed to re-engage after the red cord was pulled, or a stripped drive gear inside the motor head, which leaves plastic shavings on the housing. Each is a specific repair.

How long should a belt last once repaired?

A belt's life is counted in cycles and years, and on a balanced door with the rail straight and the tension right it runs for many years. What shortens it is a heavy door, an over-tight adjustment, a bent rail rubbing one edge, or grease on the rubber. Keep the door balanced and lubricated, the belt dry, and glance along the rail a few times a year.