Humming motor or stripped opener gears?
A motor that hums without moving the chain, belt, or trolley may have a failed start capacitor, a stalled motor, or a jammed drive. On a geared opener, a motor that runs while the drive stays still can point to stripped gears. The sound alone does not prove which part failed.
If the opener is completely silent, check the outlet power and the wall control before blaming the motor. Do not open the motor housing or keep pressing the button on a stalled opener. Switch off power if it smells burnt or overheats.
A broken spring makes the door too heavy
The torsion spring above the opening counterbalances the door. When it snaps, the opener may strain, lift a few inches, then stop. A loud bang followed by a door that suddenly will not lift is a different problem from a worn opener gear.
With the door fully closed, look at the spring from a safe distance. A visible gap in the coils is a strong sign of a broken torsion spring. Do not touch the spring, loosen its brackets, or handle the cables.
Do not force a snapped-spring door with the motor
If a torsion spring is snapped, stop using the opener. Repeated attempts can damage its drive, bend the top door section, or leave the door moving unpredictably. Do not increase the opener force setting to get past the problem.
Do not pull the emergency release on an open or partly open door with a suspected spring failure; it can drop. Keep people away from the opening and use another exit. A technician needs to secure the door, repair the counterbalance, and check the cables before operating it again.