A garage door that sits crooked — one side higher than the other — is not just an appearance problem. The door is binding, the opener is fighting physics, and something structural has given way. Most of the time the cause is a cable that has lost tension or a spring that has lost its partner.
The two most common causes
Cable slack or a cable off the drum
Each side of the door has a lift cable that wraps around a grooved drum at the top of the vertical track. When the door is closed, both cables should be taut. If one cable goes slack — because it jumped a groove, frayed and stretched, or the drum set screw backed out — that corner of the door drops. The other cable keeps pulling, so the door cocks sideways in the opening.
You can often see the difference from inside the garage. Look up at the drums. One cable will be neat and tight in its grooves. The other will have loops of slack, or it will be sitting on the flange instead of in the groove.
One spring broken, the other still winding
On a two-spring torsion system, the springs share the load. When one snaps, the surviving spring still tries to lift the door. It lifts its side. The broken-spring side stays heavy. The door twists in the tracks.
Extension springs behave the same way. If one side snaps, the other side yanks its cable and that corner rises. The door jams sideways, often bending the top section where the strut cannot compensate.
Other reasons the door sits uneven
Roller off track A single roller that has popped out of the vertical track lets that corner sag. The door will usually bind hard when you try to move it. You will hear a metal-on-metal grind as the roller drags on the track lip.
Bent track or loose track brackets A forklift tap, a car bumper, or years of vibration can bend a vertical track inward. The rollers on that side lose guidance and the door leans. Loose lag bolts on the track brackets have the same effect — the track shifts under load.
Broken bottom bracket or cable anchor The bottom fixture holds the cable loop. If the bracket cracks or the cable pulls through, that corner loses its connection to the counterbalance system. The door drops on that side immediately.
Section hinge failure On wide double doors, a failed center hinge can let the middle sag while the corners stay put. The door looks crooked, but the problem is in the middle, not the sides.
What you can check without tools
1. Stand inside the garage with the door closed. Look at the top corners. Is one side visibly lower? Measure from the floor to the bottom of the door on each side. A difference over half an inch is significant. 2. Inspect the cables at the drums. Use a step ladder. Do not touch the cables. Just look. One tight, one slack means the slack side is the problem. 3. Check the springs. Torsion springs sit on a shaft above the door. A clean break leaves a visible gap in the coils. Extension springs run along the horizontal tracks — a broken one hangs in two pieces. 4. Watch the rollers in the vertical track. Operate the door manually (pull the emergency release first). If a roller wobbles or lifts out of the track, you found it. 5. Listen. A loud bang that shook the house was a spring breaking. A gradual lean over weeks is usually cable stretch or track shift.
What you must not do
Do not try to “even it out” by forcing the door. The door weighs 150 to 300 pounds. Forcing it bends tracks, snaps struts, and shreds the remaining cable.
Do not adjust the torsion spring winding cones. The stored energy in a wound spring is measured in foot-pounds of torque. A winding bar that slips, a cone that strips, or a shaft that turns unexpectedly can put you in the emergency room. This is not a DIY repair.
Do not cut a cable to “release tension.” The spring will unwind violently. The cable will whip. The door will crash down. People lose fingers and eyes this way.
Do not loosen the set screws on the cable drums. The spring tension will spin the drum instantly. You cannot hold it by hand.
What a technician does on the call
We start by disconnecting the opener and testing the door manually. That tells us whether the binding is in the tracks, the rollers, or the counterbalance.
If a cable is off the drum, we secure the door in the open position with locking pliers on the tracks, then re-seat the cable. If the cable is frayed, kinked, or stretched, we replace both cables — they age together.
If a torsion spring is broken, we replace both springs. Mismatched cycle ratings mean the new spring carries more load and fails early. We match wire size, inside diameter, and length to the door weight, not to the old spring’s markings.
If the track is bent, we straighten it or replace the section. If the bottom bracket is cracked, we swap it. Every moving part gets lubricated with a PTFE-based spray, not WD-40.
The job usually takes 60 to 90 minutes. The door leaves balanced, level, and quiet.
Why the opener did not stop it
Your opener has a force limit and a photo-eye reversal. Neither detects a crooked door. The force limit only measures total resistance. The photo eyes only see an obstruction in the beam path. A door leaning sideways passes both tests while it grinds its rollers and bends its tracks.
When to call
If the door is more than half an inch off level, if you see a broken spring or a slack cable, or if the door binds and groans when you operate it manually — stop using it. Disconnect the opener. Call a door company.
A crooked door does not straighten itself. The longer it runs that way, the more parts you replace later.
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Call 778-873-7282 — Metro Vancouver.