Fixed the Spring Now the Cable Jumps: Second-Fault Masking Decision Tree

Why this matters

A broken spring forces the door to move with no counterbalance. Customers stop using the door, the opener struggles, and any subtle problem with cables, drums, or door balance is hidden by the dominant spring fault. Replace the spring and put the system back under load and the masked problem jumps to the front: the cable drops off the drum, the door tilts, or a frayed strand snaps. This tree forces the cable and drum inspection into the standard spring job so the second fault never becomes a callback.

Step 1: Recognize the pattern

You just replaced one or both springs. The door now balances and operates. Within minutes or hours, one of these surfaces:

• Cable drops off the drum on the next cycle.
• Cable visibly slack at full open.
• Cable visibly frayed where it sat on a worn drum groove.
• Door tilts on opening or closing.
• New banging or popping sound on cycle start.

These are not new faults caused by the spring work. They are pre-existing conditions that the broken spring was masking.

Step 2: Drum inspection

The cable drum carries the cable in a tapered groove. After a spring failure, the drum often has:

• A wear pattern from years of cable contact in one position.
• A chipped groove flange.
• Set screws that have backed off and let the drum slip on the shaft.
• A groove flattened from a cable that climbed up and rode off-track for a period before failure.

Pull the cable off the drum and inspect under a flashlight. Replace drums in pairs if either shows wear; never replace one and leave the other.

Step 3: Cable inspection

With the door fully closed and springs unwound, run the cable through gloved fingers from drum to bottom bracket. Look and feel for:

• Broken strands at any point along the length. Even one broken strand condemns the cable.
• Kinks or sharp bends, often from a prior cable jump.
• Fraying at the bottom bracket attachment, the most common failure point.
• Rust on the cable where it sat in moisture.

Replace cables in pairs, matched to the door height plus standard wrap allowance on the drum.

Step 4: Bottom bracket inspection

The bottom bracket is where the cable attaches and where the highest tension load lives. After a spring break, customers often try to operate the door manually and stress the bracket:

• Bracket bent from manual lifting on one side.
• Set screws or carriage bolts loose.
• Bracket pulling away from the bottom section because of section fatigue.
• Mounting fasteners pulled into the door panel from repeated load.

A failing bottom bracket will not survive the new spring tension. Replace if any of these are present.

Step 5: Shaft and bearings

While you have the springs off and cables out, check:

• Torsion shaft straight, no bow from impact load.
• End bearing plates square to the door, bearings free of grit.
• Center bearing plate present and aligned.
• Shaft set screws on drums and spring cones torqued to spec.

A bowed shaft will cause one drum to feed cable faster than the other and will pull cables off-track on every cycle. This is not optional to fix.

Step 6: Door section and roller inspection

The door itself often shows fatigue that the broken spring concealed:

• Top section bowed or cracked at the strut.
• Hinges loose between sections.
• Rollers worn, bearings dry, or stems bent.
• Track misaligned where a forced manual operation has knocked it.

A worn or misaligned door system will not run cleanly even with new springs and cables.

Step 7: Reassemble and tension correctly

Spool cables onto drums in the correct direction per the door manufacturer's convention. Tension drums against the door before winding springs so cables seat in the bottom groove with no slack. Wind springs per the manufacturer turn count for the door height. Verify balance by disconnect-and-lift test before returning the opener to service.

Step 8: Cycle test under load

Run the door through ten full cycles with the opener. Watch cables on every cycle:

• Cables stay seated in drum grooves.
• No popping or slipping sound.
• Both cables stay taut at full open.
• Door tracks straight, no tilt.

Any failure here means revisit step 2 through step 6. A cable that jumps on cycle eleven is a cable that will jump on cycle two hundred.

Step 9: Customer education and warranty disclosure

Tell the customer plainly: the spring break stressed the rest of the system; the cables, drums, and brackets you found worn were already on the way out. Document what was replaced and what was left as serviceable. If you chose to leave a marginal component on customer cost grounds, note that decision and the expected service interval before re-evaluation. A documented condition gate protects you when that component eventually fails.

References

• UL 325, Standard for Door, Drapery, Gate, Louver, and Window Operators and Systems
• ANSI/DASMA 102, American National Standard Specifications for Sectional Doors
• ANSI/DASMA 116, Wind Pressure Design and Spring Tension Specifications
• Door and Access Systems Manufacturers Association, Garage Door Spring and Cable Service Guidelines