You hit the close button. The door starts down looking fine. Then halfway down, one side starts dropping faster than the other — the bottom edge tilts, the panels flex, and the opener slams the door back up before it reaches the ground. You try again. Same result.
If your garage door closes unevenly and then auto-reverses, the system is telling you something specific — and almost always, the answer comes down to cable tension imbalance. With thousands of 5-star ratings across Google, Yelp, Facebook, and Thumbtack, Local Garage Doors handles this exact diagnosis weekly across California and Nevada. It’s one of the more dangerous symptoms to ignore, and it has a clear root cause most homeowners aren’t told about.
If your door is already showing this behavior, stop using it and call 
866-337-1631, 
email info@localgaragedoors.com, or schedule your appointment today. Here’s exactly what’s happening inside your door, why it’s an urgent issue, and what the repair actually involves.
What You're Actually Seeing: The Mechanics of an Uneven Close
Your garage door has two cables — one on each side of the door — that run from the bottom corner of the door panel up to the drum mounted at the top of each vertical track. As the torsion springs above the door wind and unwind, they rotate the shaft. The drums turn with the shaft. The cables wrap and unwrap around the drums, lifting and lowering each side of the door in perfect sync.
That’s how it’s supposed to work. Both sides up at the same rate. Both sides down at the same rate. Door stays level the entire travel.
When you see one side dropping faster than the other, one of those cables is no longer doing its job equally. The cable on the slow side is still pulling tension. The cable on the fast side either lost tension, is slipping on its drum, or has stretched, frayed, or shifted off its track. The result is a door that lists to one side as it drops — like a ship taking on water unevenly.
Why the Opener Reverses (And Why That's a Good Thing)
The opener doesn’t know your cables are imbalanced. What it knows is force feedback.
Modern openers monitor the resistance against the motor every cycle. When the door stops moving smoothly — because one side has stalled, twisted, or jammed in the track — the motor encounters force outside its programmed range. UL 325 safety standards require the opener to reverse direction when that happens. It’s the same auto-reverse system that protects a person, pet, or vehicle from being crushed by a closing door.
So the reversal isn’t a malfunction. It’s the system catching a real mechanical problem before the door does serious damage. The opener is essentially refusing to close a door that’s no longer balanced, because closing it would either crash the door at an angle, jam the panels in the tracks, or pull a panel loose from the hinges. We’d rather have a door that won’t close than one that destroys itself trying to.
The Six Conditions That Cause Cable Tension Imbalance
Cable imbalance doesn’t happen randomly. It comes from one of six specific causes — and identifying which one matters because the repair is different for each.
1. One cable has frayed or stretched.
Cables are made of multiple steel strands twisted together. Over time, especially in coastal Bay Area or San Diego salt air, individual strands corrode and snap. The cable doesn’t fail completely — it just stretches under load on the damaged side, letting that corner of the door drop faster. You’ll often see visible fraying near the bottom bracket where the cable attaches to the door, or near the drum at the top.
2. A cable has slipped off its drum.
Each cable spirals around the drum in a precise track. If the door was forced down manually while the springs were under tension (a common mistake during a power outage), or if the door came off track and was pushed back into place without unwinding the springs, one cable can slip out of its groove and bunch up. That side of the door no longer has consistent travel.
3. The torsion spring lost tension on one side.
On a two-spring system — common on heavier double-car doors across Sacramento, Las Vegas, and the Bay Area — the springs share the load. If one spring is older, weaker, or starting to fail, it provides less counterbalance to its side of the door. The cable on that side has to do more work, stretches under the extra strain, and the door starts dropping unevenly.
4. A cable drum has shifted on the shaft.
The drums are held in place by setscrews on the torsion shaft. If a setscrew loosens — from years of normal cycle vibration, or from a previous spring break that shocked the system — the drum can slide along the shaft. Even an eighth-inch shift changes how the cable wraps, throwing off cable length and tension on that side.
5. The bottom bracket has bent or pulled loose.
The cable attaches to a steel bracket bolted to the bottom corner of the door. If the bracket is corroded, cracked, or the bolts have backed out (we see this in older homes across Sacramento and the Sierra foothills where the original installation has been in service 20+ years), the cable’s attachment point shifts. The cable still works — but the geometry is wrong, and the door drops unevenly.
6. A roller or hinge has seized on one side.
This isn’t technically cable damage, but it produces identical symptoms. A frozen roller or a cracked hinge on one side creates resistance that side’s cable has to overcome. The door tilts during travel even though the cables themselves are fine. A proper diagnosis checks both before assuming cable replacement is the answer.
Why You Should Stop Using the Door Immediately
When a cable is failing — fraying, slipping, or losing tension on one side — every cycle accelerates the damage. And when the second side fails, several things can happen at once:
The door can come fully off track at speed. The remaining cable can snap from the doubled load, becoming a high-speed projectile in the garage. The torsion spring, suddenly seeing the full weight of the door instead of the cables holding it, can shock-load and break — which sends parts of the spring flying along the shaft. Panels can twist out of alignment and pull hinges loose, creating a domino failure that turns a $200 cable repair into a $1,500 panel replacement.
This is also when people get hurt. A door that’s already dropping unevenly is a door that’s seconds away from a catastrophic failure. We’ve responded to enough emergency calls in Sacramento, the Bay Area, and Las Vegas where homeowners kept using a door “until they could get it fixed” and ended up with vehicles trapped, doors hanging at 30-degree angles, and panels too damaged to reuse. Catching the imbalance early — at the auto-reverse stage — is when this is still a manageable repair.
What the Repair Actually Involves
Cable replacement typically runs $150–$300 depending on door size, cable gauge, and whether the issue extends to the drums or springs. Here’s what a proper repair includes — and why it’s not a DIY project.
The springs have to be fully unwound first. Cables run alongside springs that are storing 200+ pounds of torque even when the door is down. Working on the cables without de-tensioning the springs is one of the more common ways homeowners get seriously injured. We use winding bars and proper technique to unwind the springs safely before touching anything else.
We always replace cables in pairs. If one cable has stretched or frayed, the other one is the same age and has seen the same cycle count. Replacing only the failed cable is a false economy that puts us back at your house in 4–6 months when the other one fails. Both cables, both drums inspected, all setscrews retorqued, springs rewound to factory spec — that’s how the job is done correctly.
We also inspect the bottom brackets, the rollers, and the tracks during every cable repair. Cable failure rarely happens in isolation — when one component is wearing, the components around it usually are too. Catching them now is faster than coming back for each one separately.
Finally, we balance the door. Once new cables are installed and the springs are properly tensioned, we test the door’s balance manually — disconnecting the opener and lifting the door by hand. A correctly balanced door should hold at waist height without falling or rising. If it doesn’t, the springs need adjustment before we hand the door back over to you.
Where California and Nevada Conditions Make This Worse
A few specific conditions across our service area accelerate cable failure.
Coastal Bay Area and San Diego homes deal with salt air corrosion that eats through cable strands faster than dry inland climates. We see frayed cables on doors as young as 6–8 years old in Half Moon Bay, Pacifica, and Encinitas. Sacramento, Stockton, and Central Valley homes face the opposite issue — extreme summer heat dries out the lubrication around drums and pulleys, increasing cable friction and accelerating wear. Las Vegas and Henderson see the same pattern with even more intense temperature swings. Lake Tahoe, Truckee, and the Sierra foothills cycle between freezing winters and hot dry summers, which expands and contracts the steel cables repeatedly until they fatigue and stretch.
If your door is more than 8–10 years old in any of these areas and you’ve never had the cables inspected, that’s a useful annual maintenance item — included in our spring and cable inspection service. Catching wear before it becomes a failure is always cheaper than the emergency repair.
The Bottom Line
A garage door closing unevenly and auto-reversing is the system catching a cable tension imbalance before it becomes a worse failure. The cause is almost always a frayed cable, a cable off its drum, a weakened spring, a shifted drum, a bent bottom bracket, or a seized roller — and identifying which one requires opening the system up and inspecting it.
Stop using the door until a technician has assessed it. The repair is straightforward when caught early. It gets expensive — and dangerous — fast if it isn’t.
Call us at 866-337-1631,
email info@localgaragedoors.com.
🗓️Book an appointment online — same-day service available across California and Nevada.
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