Cables slipping or the door lifting unevenly? The drums may be worn.
The drums are the grooved wheels at each end of the torsion shaft. Your cables wind onto them as the door lifts.
If a drum is worn, cracked or has slipped on the shaft, the cable does not wind evenly and one side of the door lifts ahead of the other.
The door lifts crooked or binds. A cable jumps out of its groove or bunches up.
You can hear a snap or slip as the door starts to move. Often it shows up right after a cable has broken.
Most of the time drums come up while we are replacing cables, since the two work together and a damaged drum is what chewed through the cable in the first place.
We check both on every cable job rather than replacing one and leaving the cause behind.
Drums are replaced as a matched pair so both sides wind at the same rate and the door stays balanced.
The drums are the grooved wheels at each end of the torsion shaft. The lifting cables wind onto them as the door opens, which is what carries the door's weight evenly on both sides.
