The door goes up perfectly. Coming down is the trouble: partway to the floor it stops, climbs back to the top, and the light on the opener blinks at you.
The door opens about a third of the way and stops. Turning the limit screw on the head has made no difference, and the trolley seems to sit in the wrong place along the rail when the door is fully closed.
It is minus twenty in the detached garage and the door climbs in jerks, the belt stiff as a board. By the afternoon, when the sun has been on the door, it runs almost normally again.
During the ice storm the power was off for two days. You came home in the dark, found the door dead, and had to climb out of the car to pull the red cord in the cold.
Someone backed the car in a little too far, a bin or a bicycle brushed the track, and since then the door starts to close and comes back up. One sensor now sits at a slightly different angle from the other.
You bought a new remote at the hardware store, followed the little leaflet twice, and the opener light never blinked. The old remote still works.
A contractor is coming to work in the garage on Thursday while you are away. Handing over a remote means chasing it back afterwards, and the keypad code is the one your whole family uses.
Halfway up, the door lets go of the opener with a clunk and sinks back to the floor while the trolley carries on to the top alone. It has happened three times this month, and each time the release lever is found half-cocked.