Belt-Drive Opener Repair: preparing for the visit

Press the remote and the motor runs its full cycle, lights on, the usual whir, but the door does not move a centimetre. Up at the trolley, the belt is hanging loose where a small plastic clip used to hold it.

Worth answering before the call

Are there plastic shavings or grease on top of the motor housing? Is the garage heated and attached to the house, or a cold detached one? What is the belt doing: sagging, slapping, clicking, frayed, or hanging loose?

How do I know the belt is the problem and not something else?

Look and listen. A belt that hangs below the rail, slaps on the way up or clicks at the same point each cycle is a belt fault. A motor that runs with the door still might be a broken belt clip, a stripped gear or a belt off the sprocket. A door that is heavy when you lift it by hand with the operator released is a spring matter. The technician confirms which before any part is ordered.

What does out of phase mean, and why does my door stop short?

When the belt has been off the sprocket, or the motor has run without it, the motor's idea of where the door is no longer matches where the trolley sits. The door then stops short at one end however the limits are turned. The technician lifts the belt off, runs the sprocket to its closed position, refits the belt with the trolley at the closed end and relearns the limits.