What causes a garage door cable to fall off?

A garage door cable can fall off its drum or become loose due to several mechanical and operational issues that cause slack and misalignment. The most common cause is operating the door with a broken or weak spring, as springs provide tension that keeps cables taut around drums; when a torsion or extension spring breaks, cables lose tension and fall off drums immediately. Another common cause is manually opening or closing the door too quickly or unevenly after pulling the emergency release cord, causing one side to move faster and cable to derail. Hitting the door with a car or obstruction while opening or closing can bend tracks and cause rollers to bind, leading to cable slack. Cables that are old, frayed, rusted, or kinked are more likely to slip off because they do not seat properly in drum grooves. Improper installation where cables are not properly seated in drum grooves or bottom brackets, or are wrong length for door height, causes them to fall off. Doors that are unbalanced due to incorrect spring tension cause uneven pulling and cable derailment. Attempting to lift door that is frozen to ground or has debris in tracks creates sudden slack. Worn drums with grooves worn smooth allow cable to slip. To prevent cables falling off, keep springs maintained, keep gutters clean to prevent rust, lubricate rollers, avoid hitting door, and have professional annual inspection to ensure proper tension and alignment.