Fortunately the repair is neither difficult nor expensive and it should only take an hour of your time.
Replacing worm gear craftsman garage door opener.
This was a craftsman model 139 53976srt.
Slide the new drive gear onto the drive shaft and line up the mounting hole in the drive gear with the hole in the drive shaft.
Tried to adjust up and down limits with not success.
This is a video on how to change the gear sprockets in a craftsman garage door opener.
Insert the new roll pin through the gear and drive shaft.
I did the repairs with the door fully closed.
Use a punch and hammer to drive the roll pin out of the drive shaft.
Flip the motor unit over.
Replaced gear and worm on craftsman 139 53970srt.
Shredded plastic gears are a common problem with chain driven garage door openers.
Remove the gear and sprocket assembly.
Door now opens about 1 foot and stops.
Remove the screws from the chain spreader and pull the chain spreader off the motor unit.
Step by step garage door opener gear fix.
Remove the light covers and light bulbs from the motor unit.
Replace the drive gear.