Garage Door Cable Off the Drum: What Happened and What to Do

Look at the top corners of the door with it closed. Normally each cable runs taut from the bottom bracket of the door straight up to a drum at the end of the spring shaft, and winds neatly into the drum's grooves. When one has jumped, you'll see slack: a cable hanging in a loop, lying across the top of the door, or wound back on itself in a tangle on the drum.

The door tells you too. It sits crooked, one side higher than the other. It jams part way, or scrapes one side of the track. The opener strains, reverses, or the door drops onto one corner with a thud when it closes. Clopay lists slack or sagging cables, a wobbling door, and cables slipping off the drum as the warning signs of cable trouble, and they're usually all there at once.

A cable only stays on its drum while there's tension on it. Anything that lets the door's weight off the cable for a moment lets the cable go slack and jump a groove, and then it winds back on crooked or not at all.

The cause we see most in Winnipeg is a door that's frozen to the floor or caught on something while the opener pulls up. One side lets go first, the other cable goes slack, and off it comes. The frozen door guide exists mainly to prevent this. A broken spring does the same thing, because the spring was what kept the cable tight. A worn, fraying cable can also stretch or snap, and a door that's been running out of alignment doesn't seat its cable in the drum properly, so the cable wears and unravels without much warning.

Stop. Don't press the button again: every cycle with a cable off tightens the tangle, bends the track, and can tear the bottom bracket out of the door. Don't pull the red release cord if the door is anything but fully closed, because a door with one cable gone is being held by the opener on one side and by nothing on the other, and it can drop. And don't try to lift, straighten, or push the door into line; it's heavy, it's unbalanced, and it can move suddenly.

If the door is closed, leave it closed. If it's stuck part way, leave it where it is, keep people and cars clear of it, and call. This is one of the few garage door problems where leaving it alone is the whole of the right answer.

Because the cable is one end of the spring system. Seating it properly means taking the spring tension off, re-seating and levelling both sides, and putting the tension back on, which is winding-bar work. Clopay's advice on cables is blunt: don't try to adjust the tension yourself, and a snapping cable can lash out with enough force to embed itself in wood. LiftMaster's manuals say the same about cables, pulleys, and brackets: all under extreme tension, never adjust them.

The actual repair is quick for a technician. We check why the cable came off, replace it if it's frayed or kinked, replace both cables if one has worn since they wear together, re-seat and level the door, and check the spring, drums, and bottom brackets while the tension is off. It's covered on our cable and roller repair page.