Overview
Lift cables run from the spring's cable drum down to the bottom roller bracket on each side of the door. They're under constant tension and routed around pulleys and through drums that have to stay properly seated for the door to track evenly. A cable that's even slightly frayed is a matter of when, not if, it lets go completely — and once it does, that side of the door drops while the other stays up, putting serious stress on the track, rollers, and the remaining cable.
When You Need This
The giveaway signs are a door that looks tilted in the opening, visible fraying near the bottom bracket or the drum, a cable that's come off its drum entirely, or a door that suddenly stops mid-cycle and won't continue. Cables wear faster on doors that get cycled a lot — a garage used daily, or a household running multiple vehicles in and out — and rust along the coast can corrode the wire strands from the inside out before it's visible from the floor.
