Opener runs but door won't movewhat is slipping, stripped or broken

Check whether the trolley is disengaged from the emergency release. If it is engaged, try the door by hand with the release pulled and the door closed. A heavy door means a broken spring; a light door with a running opener points to a stripped gear or broken chain or belt.

After someone pulls the release, the trolley rides along the rail without the door. Re-engaging it per the manual fixes it.

The motor turns but the gear teeth slip. A technician replaces the gear after checking the door's balance.

The opener cannot lift a door without spring help. It may hum, strain or lift a few inches. Fix the spring first.

Repair if the opener is otherwise sound; replace if it is old or lacks safety sensors.

Storm surges damage boards; ice-frozen doors strip gears.

On chain-drive openers, a loose chain can slip off its sprocket, letting the motor run without moving the trolley. A broken belt on a belt-drive opener does the same. Chains can be retensioned according to the manual; broken belts and damaged sprockets need replacement parts. If the chain hangs well below the rail or the belt is visibly torn, call a technician.

Screw-drive openers use a threaded rod. In very cold or very humid conditions, the grease on the rod can stiffen or wash off, and the trolley may bind. Cleaning and re-greasing with the specified lubricant often restores operation. If the trolley threads are stripped, the trolley needs replacing.

Wall-mount or jackshaft openers turn the torsion shaft directly. If the motor runs but the shaft does not turn, a set screw or coupling may have slipped. If the shaft turns but the door does not lift, a spring or cable has likely failed. These units should be serviced by a technician familiar with them.

When a door will not move, it is tempting to increase the opener's force setting. That may make the opener lift a door with a broken or weak spring for a while, but it strains the motor and gear and can defeat the safety reversal. Fix the door problem and leave the force at the proper setting.

The trolley that rides the rail has its own wear parts. A cracked trolley or worn release mechanism may let the trolley disengage on its own, so the motor runs but the door stays. Replacing the trolley restores the connection.

Very old openers may have parts that are hard to find. If a gear or trolley fails on an opener that also lacks modern safety features, replacement is usually the better route.

After repair, run the door through several cycles, confirm it stops at the right positions and test the safety reversal by contact and by breaking the beam. If anything seems off, stop using the opener and call back.

Kids and visitors sometimes pull the red release cord out of curiosity, leaving the trolley disengaged. The next time the button is pressed, the trolley moves without the door. Re-engaging it per the manual solves the problem. Some homeowners tie the cord up out of easy reach while keeping it accessible for adults.

A heavy insulated or wood door can wear out a light-duty opener's gear quickly, especially if the springs are not perfectly balanced. If gears keep stripping, the springs may need adjusting or the opener may be undersized for the door. A technician can check both.

Some openers lose their limit settings or remote programming after a power outage or surge. If the door stops short or remotes stop working after a storm, the opener may need resetting according to the manual.

If the trolley is engaged, the door moves freely by hand and the opener still will not move it, the problem is inside the opener. Rather than opening the motor unit, call a technician.

If the motor runs, the remote and wall button are working. The problem is between the motor and the door, or the door itself.