Off the track
A door sitting crooked in the opening, or jammed at an angle, has come off its rollers on one side. Everything else on the door is still under tension, which is why this is a stop-using-it situation rather than a try-it-again one.
Call before using it againLicensed technicians · no obligationWhat puts it there
Something in the way. The commonest cause anywhere: a bin, a bicycle, a snow shovel left leaning where the door comes down. The door lands on it, one side stops and the other keeps going, and a roller leaves the rail.
A cable off its drum. If a lift cable slips off the drum at one end, that side loses support and drops. The door then hangs at an angle on one cable, which is both the symptom and a hazard.
Salt-eaten rollers and track. This is the local one. Brine drips off the car onto the bottom of the track and the lowest rollers, and corrosion there stiffens the roller bearings and roughens the rail. A roller that no longer rolls skids instead, and a skidding roller climbs out of the track at the first awkward moment.
A bent rail. Reversing into the track even lightly bends it, and a door will tolerate that for months before jumping out on a cold morning when everything is stiffer.
Why not to run the opener
The opener will happily pull a door that is already out of its track, and the result is predictable: more rollers come out, panels bend at the hinges, and a repair that was a roller and an alignment becomes a panel replacement. Each attempt enlarges it.
What a sensible repair looks like
The door is secured and the tension taken off before anything is moved back. The rail is checked for bends along its length rather than only at the obvious spot, the rollers are looked at as a set because they have worn together, and the cables are checked at both drums for fraying at the point they left.
In this climate the bottom rollers and the lowest two feet of track are worth replacing rather than cleaning when they have gone. Corrosion there returns.
Keeping it in the track
Keep the landing strip clear; rinse the salt off the bottom of the tracks at the end of winter; and if a roller squeals in the cold, treat it as a warning rather than a nuisance. A seized roller is the one that comes out.