What the Fix Involves
We start by identifying which cable system is actually on the door - extension-pulley or torsion-drum - because the parts, the tension setup, and the safety steps aren't interchangeable. For an extension system, that means releasing tension on both springs, pulling the old cable off the pulley and the bottom bracket, and running a replacement of the correct gauge and length. For a torsion system, the cable comes off the drum, and the drum has to be reset to the same number of turns it had before, or the door goes up crooked. Either way we check the bottom bracket the cable anchors to, since a bent or rusted bracket is often what actually caused the cable to jump or fray in the first place, not just wear. We also check the opposite side cable even if it looks fine - if one side failed from age or corrosion, the other side is usually close behind. We test the door through a full cycle before we call it done, watching for drift, uneven travel, or a track that binds. If the springs themselves are shot rather than just the cable, that's a separate repair, and we'll say so before starting rather than after.
The Symptom
The most common call we get for this is a door that suddenly sits crooked in the opening - one corner low, the panel racked at an angle - or a door that won't move at all and has a visible loop of loose cable hanging near the bottom bracket. Sometimes it's less dramatic: the door runs rough for a few weeks, catching partway up, before the cable finally lets go. On extension-spring setups, a frayed cable can also slip off the pulley without fully breaking, which makes the door lift unevenly on one side before it jams. If you hear a bang followed by the door refusing to open, that's usually the cable or the spring itself letting go under tension, and it's not a job to force through with the opener. Don't keep hitting the remote - running the opener against a jammed or off-track door usually turns a cable repair into a track and roller repair too.
Parts We Carry
We stock galvanized lift cable in the common gauges and lengths used on extension-spring residential doors, along with the drums, bottom brackets, and pulleys that most often fail alongside the cable itself. For torsion setups we carry matched cable sized to standard drum diameters. What we don't keep on the truck is every proprietary cable length used on architect-specified or custom insulated doors - those sometimes require an order from the door manufacturer, which can add a day or two before we can finish the job. At 16 miles out from Philadelphia, this is one of the farther stops on our route, so we try to confirm the door type and rough door size before we head out, which cuts down on a second trip for a part we didn't bring the first time.
