Garage door symptoms
The opener is running but my garage door isn't moving
When the opener runs but the garage door doesn't move, something between them has let go. Most often the red release cord has freed the trolley, a quick fix at home; if the chain or belt sits motionless, the drive gear has probably stripped.
Updated
Opener runs but the door won't move? Watch the rail first
Press the wall button once more and look up: whether the chain or belt moves, and whether the trolley rides along, shows where the break is. Then unplug the opener so the motor stops grinding at a problem it cannot solve. If the door is open or stuck partway, leave the red cord alone and let us check the springs; we serve the whole Portland area.
Likely causes, most common first
A trolley freed by the red cord is the usual break, then a stripped drive gear.
- Most common
The trolley is released from the door
The sign: The chain or belt runs and the trolley travels the rail, but the carriage holding the door arm stays parked by the door, often after the cord was pulled in an outage or snagged by a stepladder.
The fix: Latch the trolley back onto the carriage, and replace the trolley or its release spring if the latch keeps slipping free. Garage Door Opener Repair, from $149
- Common
The drive gear inside the motor head stripped
The sign: The motor whirs at full speed while the chain or belt does not budge, and white crumbs may be scattered on the floor below the opener head.
The fix: Open the head and replace the worn gear together with its sprocket, greased before the first run. Garage Door Opener Repair, from $149
- Common
A spring broke and the opener cannot lift the door
The sign: The trolley lurches, the door rises an inch or two or not at all, and the opener quits or backs off; on the torsion shaft over the door, one coil has separated.
The fix: Replace the broken spring, balance the door, and inspect the opener gear for wear from the strain. Garage Door Spring Replacement, from $249
- Less common
The chain, belt or sprocket broke
The sign: A chain hangs slack along the rail, a belt has snapped or shed teeth, or the sprocket on top of the motor head spins without catching anything.
The fix: Replace the broken chain, belt or sprocket and set the drive tension so the trolley tracks straight. Garage Door Opener Repair, from $149
- Less common
The door arm tore loose from the top section
The sign: The trolley and door arm move together, but the arm swings free because its bracket ripped out of the thin steel of the top section.
The fix: Reinforce the top section with an operator reinforcement bracket or strut, remount the arm, and replace the section if the steel is split. Garage Door Panel and Section Replacement, from $449
What you can safely check in two minutes
Each check takes seconds, by eye, with your hands away from anything under spring tension.
- Find the red release cord. If the trolley sits apart from the carriage near the door, the door was disconnected rather than broken.
- Run the opener once and watch the rail. A moving chain or belt means the motor and gear work; a still chain under a busy motor points at the gear.
- Check the floor under the motor head for white plastic crumbs, the usual leftovers of a stripped gear.
- Look at the slide lock handles on the inside of the door. A bolt pushed into the track will hold the door against the opener.
- From the floor, scan the springs over the door opening for a coil that has pulled apart.
What moves and what stays still tells you where it broke
A moving chain with a parked carriage means a released trolley you can relatch; a still chain under a running motor means a stripped gear.
| What moves | What stays still | Most likely cause | Who fixes it |
|---|---|---|---|
| Motor sound only | Chain or belt, trolley and door | Stripped drive gear or broken sprocket | Opener repair visit |
| Chain or belt and trolley | Carriage and door | Trolley released by the red cord | Usually you, in a minute |
| Chain, trolley and door arm | The door itself | Door arm torn from the top section, or a slide lock engaged | Unlock it, or book a repair |
| Trolley jerks a few inches | Door, which feels heavy | Broken spring | Spring replacement |
| Motor and sprocket | Slack chain, trolley and door | Broken chain or belt | Opener repair visit |
When it is safe to reconnect the trolley yourself
It is safe when the door is fully closed, both springs look whole, and the door is not stuck or crooked. In that case latching the trolley back on is a normal homeowner job.
Plug the opener in and run it with the wall button. The trolley on most chain and belt units rides toward the door and snaps onto the carriage. Some models want a tug on the cord in a set direction first, so check the manual if it glides past.
A trolley that lets go again by itself needs a part, not another reset. A worn latch, a weak release spring or a cord that catches on a car rack will keep separating the door from the opener.
Why a stripped gear is rarely just bad luck
A drive gear usually strips because it spent months pushing harder than it should have, so replacing it without asking why invites a repeat.
Opener makers treat white shavings inside the head as the signal to replace the gears, and those shavings are worn teeth. Weak springs, dry rollers or a track that pinches the door add load on every trip until the teeth slip.
So a gear job here starts with the door. We disconnect it and lift it by hand, and if it will not hold its place halfway, the springs get adjusted or replaced first. On an older opener without photo eyes, a new unit may be the better call, and you see both prices before deciding.
Call instead of resetting if you see any of these
Book a repair rather than retrying when the door or opener shows any of these.
- The motor hums along while the chain or belt stays parked.
- White plastic crumbs keep turning up under the motor head.
- The door is hard to lift by hand, drifts down, or sits crooked.
- The trolley reconnects, then lets go again within a few cycles.
Opener runs, door stays put: common questions
Why does my garage door opener run but the door stays shut after a power outage?
Usually the red release cord got pulled during the outage and the trolley never latched back on. With the door closed, press the wall button and watch the trolley travel to the carriage and catch. If it slides past without catching, pull the cord the way your manual shows and try again, and call if it still will not hold.
Can I keep using the opener if the motor runs but the chain does not move?
No, unplug it until the gear is replaced. Each extra run grinds the stripped teeth further and heats the motor while the door goes nowhere. If you need the car tonight and both springs look whole, pull the release cord with the door down on the slab and open it by hand. A gear and sprocket swap is one of the more routine opener repairs.
Why does the trolley move along the rail but my garage door does not?
Because the trolley is no longer connected to the door, either at the release latch or at the door arm bracket. Look first at the carriage near the door: if the trolley sits apart from it, the cord was pulled. If they are joined and the arm still swings loose, its bracket has torn from the top section and needs reinforcing.
Can a broken spring make the opener run without moving the door?
Yes. An opener only steers a door that the springs are already holding up, so when one breaks the motor may lift an inch or two and then quit or reverse. Check the springs over the door for a separated coil before running it again, and leave the release cord alone if the door is open.
What should I photograph when my opener runs and the door will not move?
Send three photos: the label on the motor head, the rail showing where the trolley sits, and the springs over the door. The label tells us the model, so the right gear kit or trolley comes along. The other two often settle whether it is the trolley, the gear or a spring.
Related pages
Areas we cover for this
Calls about a opener runs, door stays put come in from Lake Oswego, Piedmont and Humboldt, Southwest Hills and Council Crest and every other part of the metro we serve.
Ready to get the door moving again?
Call with the symptom, or text a photo of the door and the opener, and we will name the part and the posted price before anyone drives out.