You go to raise the door, and it lurches up crooked, one side lagging behind the other. Down the wall, a thin steel cable that should be taut is hanging slack, or worse, coiled in a loose nest on the garage floor.

One corner of the door is riding lower than the other. There is a wedge of daylight where the door should meet the frame, a roller dangling off its rail, and the whole thing looks like it is leaning against the opening instead of hanging in it.

It usually happens on an ordinary morning. You hit the wall button on your way out. There is a bang from the garage, like someone dropped a bowling ball on concrete, and the door lurches and stops. Now the opener hums, the door sits there, and your car is stuck behind it.