GarageDoor

Chamberlain Lift-Master 1/3 HP model no: 1050-6

  • East s/n: 0944S01344
  • Mid s/n: 0944S01346
  • West s/n:

Included in the replacement Sprocket and Gear Assembly: 041C4220A (new) 41A2827 (old)

  • pre-assembled drive shaft with sprocket and drive gear, and helical gear and retainer clip
  • replacement motor worm gear
  • tube of white grease
  • instruction sheet
2019-03-15 - East Door - Drive Gear assembly replacement

Yesterday, the garage door stop halfway up with the motor rumbling away but not moving the door. After looking into the unit, it was clear that the drive gear had shreded with all the teeth sheared off.

Turns out that I had a last of three drive gear replacement assembly on hand and I was able to make the repair without difficulty using the instruction sheet included with the repair kit.

I first had to loosen the chain so that I could slip it off of the drive sprocket and raise the garage door. Once that was done, the repair followed these steps:

  1. Loosen the drive chain and remove from the drive sprocket
  2. Remove the front and rear light lenses and the light bulbs
  3. Remove the front and rear recessed slotted screws on the bottom rim of the plastic housing
  4. Remove two screws from each side, then remove the metal opener cover \\ Once inside I could see that the nylon drive shaft gear that meshes with the motor worm gear was shredded with white dust and filings littering the lower bracket. The motor work gear was in great shape though, and I elected to keep the old one installed. Otherwise, replacement of the motor worm gear involves disconnecting the wiring and removing the motor and mounting bracket.
  5. remove the helical gear retainer clip from the bottom of the drive shaft, then slide the helical gear off the shaft
  6. Remove the three screws holding the sprocket gear assembly from under the upper bracket
  7. Lift the sprocket and gear assembly up and out of the opener

The process took about 15 minutes to remove the old assembly.

Putting the replacement into the opener simply follows the reverse procedure, noting the following

  • The three screw holes in the mounting plate of the new assembly are not tapped; the screws are self-tapping. So it turned out to be a lot easier to drive the screws through each of the three holes on the bench before trying to attach the assembly to the opener itself. I drove the screws, then removed them again, then mounted the plate with the holes already threaded.
  • I applied some the supplied white grease to the bushings supporting the drive shaft, both at the top mounting plate and on the bottom of the shaft before mounting the plate.
  • As instructed I applied the supplied white grease liberally to the worm gear and the new drive gear before closing the housing.