Your garage door opener hums or runs, but the door won't move. What to check first
When the opener motor runs and the door stays put, the cause is often simpler than a failed opener. Here is what the manufacturer lists, the check that costs nothing, and where a worn drive gear fits in.
You press the button. You hear the opener hum, or the motor run. The door does not move.
Not sure which problem this is? Start with our page on a garage door that won't open.
It feels like the opener has died. It may not have. Chamberlain's B980 owner's manual has a line for exactly this in its diagnostic chart (page 40): "Opener hums for 1-2 seconds no movement." The fix it gives starts with the door, not the motor.
Check 1: is the door still attached to the opener?
If the emergency release handle has been pulled, the door is disconnected from the opener's trolley. Chamberlain's B980 manual (page 35) gives the way back: "Pull the emergency release handle toward the garage door opener so the trolley release arm snaps to the horizontal position. The trolley will reconnect on the next UP or DOWN operation, either manually or by using the door control or remote control."
Our own guide to what to do when the power is out also covers the release cord. Chamberlain has a separate guide on how to manually open or close a garage door. Its warning says to use the emergency release only when the door is fully closed, if possible, and never to pull the release handle to raise or lower the door. It adds that weak or broken springs can make a door drop fast with no warning.
Check 2: could it be a spring?
Chamberlain's B980 manual names a broken spring among the things to check for when the opener hums with no movement (page 40). It also says repairs to cables and spring assemblies, "ALL of which are under EXTREME tension, MUST be made by a trained door systems technician" (page 34).
Our rule: if you can see a gap in a spring, or the door feels unusually heavy, stop and call a garage door technician. Do not lift the door, and do not wind or replace anything yourself. Skip the chart's step of moving the door by hand if you suspect a spring.
If your door has a manual lock
If your door has a manual lock on it, unlock it before you try the opener. Chamberlain's B980 owner's manual lists a door lock, next to a broken spring, among the things to check when the opener hums with no movement (page 40), and on page 2 it says to disable all locks before operating the opener. LiftMaster's 87504 owner's manual (page 4) says the same.
The red pull cord is a different part: it is the emergency release that disconnects the door from the opener. Chamberlain's manual-open guide says to use it only with the door fully closed, if possible, and never to pull the release handle to raise or lower the door. It also says that if the door feels unusually heavy or will not stay open, stop and contact a garage door professional. Springs and cables are always a job for a pro (our rule).
Where a worn drive gear fits
LiftMaster sells kits to replace the drive gears inside an opener. Its chain drive gear and sprocket kit includes a helical gear and top hat assembly, a worm gear, wear bushings and grease, and its drive gear and worm kit includes a helical gear, worm gear, grease and wear bushings. Both pages say the kits are for LiftMaster and Chamberlain openers made after 1993 only, and tell you to check the owner's manual or replacement parts diagram before ordering. Which drive type you have (chain, belt or screw) is covered in belt vs chain vs screw drive openers.
The manufacturer pages do not describe symptoms or give installation steps, so what follows is ours, not theirs. A worn gear is one cause a technician may check when the motor runs, the chain, belt or screw is not moving, and the door is correctly connected. We cannot tell you from a description that it is your cause.
What a part costs
LiftMaster listed the chain drive gear and sprocket kit at $50.99 and the drive gear and worm kit at $27.99 when we checked its pages on October 14, 2026. Those are parts only, for the models each page names. We do not have a sourced figure for having one installed.
Who should do the swap
This part is our advice: have a garage door technician confirm the cause and do the swap. Replacing a gear means taking the opener apart, with the door held safely while it is apart. Chamberlain's B980 manual (page 34) says to "ALWAYS disconnect electric and battery power to garage door opener BEFORE making ANY repairs or removing covers." If the opener is old enough that you are weighing repair against replacement, how long a garage door opener lasts and our repair guide help with that decision.
What to do today
- Unplug the opener, or pull its power, before you touch anything.
- Check that the door is closed and attached. Use the emergency release as Chamberlain describes.
- If the door feels unusually heavy, will not stay open, or slams shut, stop. Chamberlain's manual-open page says to "STOP immediately and contact a garage door professional" when that happens. Our rule adds two more: stop and call if you see a gap in a spring or a frayed or kinked cable.
- If none of that explains it, call a technician and give them the opener model number from its label.
