If a lift cable snaps, stop operating the door. One side may be carrying more load, the door can become crooked, and the remaining cable, spring and track hardware can be overloaded.
Keep clear of the door
Do not stand beneath a partly open or crooked door. Keep vehicles and people away and do not attempt to guide the door by hand while one side is unsupported.
A cable failure has a cause
Corrosion, fraying, incorrect tension, a damaged drum, obstruction or uneven door travel can contribute to failure. Replacing only the visible cable without finding the cause can lead to another release.
Do not remove the bottom bracket
Lift cables commonly connect at the bottom fixtures, which may remain under spring force even when the cable appears loose. Those fasteners are not ordinary adjustment points.
Inspect the complete lifting system
Both cables, drums, springs, bearings, bottom fixtures, rollers, tracks and door alignment should be checked. Equal cable tension and controlled travel must be verified after repair.