Slipped Cables and the Door That Hangs Crooked

A cable that has jumped its drum nearly always did so because something else went first. The door was closed onto an obstruction and went slack on one side, or a spring broke and dropped all the tension at once, or the set screws holding a drum to the shaft worked loose. Winding fresh cable onto a drum that is not properly located simply repeats the fault a few weeks later.

So the drums come into it every time. Both have to be locked at matching points on the shaft, both cables wound with the same number of turns, and the tension evened before the springs are brought back up. Out by half a turn and the door will sit visibly off level in the opening, which is the thing homeowners notice from the street.

The door is supported and the spring tension taken off before anything is unbolted, because cable work happens inside a system that is still fully loaded. New cable is cut to the height of your door, seated in the bottom brackets and wound onto re-set drums, then the door is cycled by hand and watched for any wander.

While it is apart we look at what killed the old one. Bottom brackets get checked for corrosion, the bottom section for rust or rot around its fixings, the rollers for the flat spots that make a door snatch, and the springs, since a spring near the end of its life is one of the commonest reasons a cable goes early. You are told what turns up, and nothing beyond the cable work happens without you agreeing to it.