Belt-Drive Opener Repair: what to note first

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

Does the door lift easily by hand and stay put halfway with the opener released? How wide is the door, and is it a single or a double? When did the trouble start, and did it follow a power cut or a pulled red cord?

Can a belt from any opener be used, or does it have to match?

It has to match. Belts are made in lengths for particular rails, so a 7 ft door rail and an 8 ft rail take different belts, and the teeth must match the sprocket's pitch. The clip or link that joins the belt to the trolley also differs between makers. The technician reads the model from the head unit's label and brings the belt made for it.

Why is the door tested by hand before the belt is touched?

Because the belt guides the door; the springs carry it. A door that lifts with moderate effort and stays put a metre off the floor is balanced, and a belt on that door lasts. A door that drops or drifts is loading the belt, trolley and sprocket far beyond their design, so a new belt would wear the same way. Spring work comes first in that case.