Opener Runs but the Garage Door Does Not Move
If the opener runs but the garage door does not move, the most likely causes are a stripped gear and sprocket kit, a disengaged or broken trolley, or a snapped chain or belt. All three are opener repairs at $95 to $300 rather than replacements, provided the unit is not already past its useful life. In Florida the gear strips early because the plastic softens in a 100°F garage and because the door has usually been out of balance for a while.
What is actually happening
The motor and the door are connected through a chain of parts: motor, gear and sprocket, chain or belt, trolley, arm, door. If the motor runs and the door does not move, one of the links in that chain has broken.
Which one is usually obvious from watching it for a few seconds.
The rail does not move at all. The failure is between the motor and the chain: a stripped gear and sprocket kit. This is the most common opener failure there is.
The chain or belt moves but the door does not. The trolley has disengaged from the carriage, or the arm connecting it to the door has broken or bent.
The chain or belt is hanging loose. It has snapped or come off the sprocket.
Before any of that, one check: if the door is closed and you did not hear a bang, this is the opener. If the door is closed and you did hear a bang, look at the spring first, because the loud bang guide applies and the opener may be fine.
Stripped gear and sprocket
Inside the motor housing there is a plastic gear driving the sprocket that turns the chain. The plastic is the sacrificial part by design: it is cheaper to replace a gear than a motor.
It strips for three reasons that overlap in Florida. Age, because the plastic gets brittle. Heat, because a garage in Orlando or Fort Myers sits above 100°F all summer and the opener lives at the ceiling where it is hottest, which softens the gear teeth. And load, because the door has been out of balance and the opener has been lifting weight the springs should have been carrying. Someone pressing the button repeatedly on a jammed or spring-broken door finishes it in an afternoon.
The signs: grinding or a rattle from the housing, the rail still, and often a pile of plastic shavings on top of the unit or on the floor under it.
A gear kit replacement is an opener repair at $95 to $300 including labor, and it is a routine job on LiftMaster, Chamberlain and Genie chain drive units.
Important: if the door was out of balance and that is what killed the gear, fitting a new gear without fixing the springs buys you another year at most. We check the balance on every gear job and tell you what we find.
Disengaged trolley
The manual release cord disconnects the trolley from the carriage so the door can be moved by hand. In Florida it gets pulled a lot: every power outage after a storm, every time the GFCI trips, every time someone needs the car and the opener is dead. If it has been pulled and not re-engaged, the opener runs the carriage up and down the rail with nothing attached, and the door sits still.
Re-engaging is usually a matter of pulling the door closed by hand and then running the opener until the carriage clicks back into the trolley. Some models need the release lever pushed back toward the door first. Our manual release guide has the steps by brand.
If it will not re-engage, the trolley itself may have cracked, which is a common failure on units that have been run against a heavy door. That is a trolley replacement inside the $95 to $300 opener repair range.
A bent or broken door arm looks similar: the trolley moves, the arm flexes or hangs, and the door stays. This usually follows an opener being run on a door with a broken spring, and it is worth checking the top section for a crease at the same time, because a creased top panel is a panel replacement at $250 to $800.
Snapped chain or belt
Less common, and usually the result of long neglect, a door that jammed hard, or a chain that rusted through. Salt air near the coast and the daily humidity everywhere else corrode a chain that has never been lubricated, and a rusted chain stretches, skips the sprocket, and eventually parts. A belt that has been baked through ten Florida summers cracks and separates at the splice.
Replacing the chain or belt is an opener repair at $95 to $300. A belt that has snapped on a unit under ten years old is unusual and worth asking about, because the underlying cause is often that the door has been heavy for a long time.
What it costs
| Cause | What to check | What it costs |
|---|---|---|
| Stripped gear and sprocket | Motor grinds, rail still, plastic shavings on the unit | $95 to $300 opener repair |
| Trolley disengaged | Carriage runs the rail, door still, release cord was pulled | Nothing to re-engage yourself |
| Trolley or carriage cracked | Will not click back in | $95 to $300 opener repair |
| Bent or broken door arm | Trolley moves, arm flexes, door still | $95 to $300 opener repair |
| Snapped or rusted chain or belt | Chain hanging loose or off the sprocket | $95 to $300 opener repair |
| Top panel creased by the opener | Bend at the arm bracket | $250 to $800 per section |
| Springs out of balance behind it all | Door will not hold halfway by hand | $150 to $350 per spring |
| Opener not worth repairing | Pre-1993, over 15 years, parts unavailable | $275 to $600 new opener installed |
Every figure is the same one on our prices page, a starting price for a standard single door in normal condition.
Repair or replace the opener
A gear kit on a ten year old chain drive with a balanced door is an easy yes. A gear kit on a unit that predates photo eye sensors, or one that has already had a board and a capacitor, is money that should go toward a new opener. Old garage door opener safety explains the 1993 line.
A new chain drive runs $275 to $450 installed and a belt drive $350 to $600; the full comparison is in belt versus chain drive. Whichever you choose, in Florida we add battery backup at $60 to $150, because the next storm outage is the moment you will want the door to work without pulling the release. Opener installation is quoted before we arrive, and replacing only the opener normally needs no permit.
The question behind all three
Every one of these failures is made far more likely by a door that is out of balance. An opener is designed to guide a door that the springs are already holding, not to lift a heavy one.
Before spending money on the opener, pull the manual release with the door closed and lift the door halfway by hand. If it does not stay where you leave it, the springs are the real problem, and the opener is the thing that has been paying for it. Spring replacement at $150 to $350 per spring fixes the cause; the gear kit fixes the symptom. On most calls we do both, and the opener then lasts.
Where we work
Same-day opener repair across Central Florida, Tampa Bay, Southwest Florida, Miami-Dade County, Broward County, Palm Beach and the Treasure Coast and North Florida. Call (561) 897-9930 and tell us the brand on the motor housing and whether the chain moves. We carry gear kits for the common units on the truck.
Related questions
What does a stripped opener gear sound like?
A grinding or rattling from inside the motor housing while the rail and chain stay still. It is a distinctive sound and once you have heard it you will recognize it. The plastic gear inside has lost its teeth, and you will often find white or tan plastic shavings on top of the motor unit.
Is a gear kit worth fitting on an old opener?
On a unit under about fifteen years old with no other problems, yes, at $95 to $300. Past that, or if the opener predates 1993 and has no safety sensors, put the money toward a replacement at $275 to $600 installed, ideally with battery backup.
The door moves an inch and stops. Is that the same thing?
No. That is more likely a broken spring or an obstruction in the track. A gear, trolley or chain failure means the door does not move at all while the motor runs. If you heard a bang first, read our broken spring guide instead.
Why does the gear strip in the summer?
Two reasons that stack. A Florida garage runs above 100°F for months and the opener is mounted at the ceiling where it is hottest, which softens the plastic gear. And a door that has been getting heavier as the springs wear makes the opener work far harder than it was designed to. The gear is the sacrificial part, so it goes first.
Can I re-engage the trolley myself?
Yes. Close the door by hand, then either pull the release cord toward the door to reset the lever, or simply run the opener and let the carriage travel until it clicks into the trolley. If it will not click in, the trolley or the carriage is broken and that is a repair.
