This video from sears partsdirect shows how to replace the chain and cable assembly on a chain drive garage door opener.
Garage door chain drive fix.
If there are some you can use a wood block and your hammer to fix the dents.
A new front sprocket costs about 150 200 include the labor to install it.
If the motor hums but the chain doesn t move that indicates a problem with the motor.
Press the remote or the wall mounted start switch listen to the motor and watch the movement of the chain.
Start by checking the things below to see if it is the problem lies with the garage door.
Sprocket is at the end of the opener rail closest to the garage door opening.
The chain wraps around this sprocket as well as the gear and sprocket at the motor.
Slide the pulley toward the garage door until the chain is stretched tight then move it toward the motor until the middle of the chain touches the upper side of the chain arm.
Located along the rail the chain an.
Examine the metal tracks on the door for dents or bumps.