Drive Gear 81B0045 for Liftmaster Chamberlain Craftsman Sears Garage Door Opener 41A2817 41C4220A

Innenbohrungen ist nicht 12,7 mm sondern 13,00 mm und der Maß zwischen den Spannstiften ist zu klein

My Craftsman garage door opener Model 139.53640SRT from September 1995 had stopped working. The motor would run for a few seconds but the chain didn't move. On closer inspection, I saw that the chain drive sprocket on the top of the drive was not turning. I unplugged the drive, removed the cover and saw that the drive gear teeth were nearly gone and there was a pile of shredded white plastic on the bottom of the cover. I had replaced the gear 10 years ago. I have a 16-ft wide all wood door so it is lifting a fairly heavy door. This replacement drive gear arrived within 2 days. I had forgotten the steps to replace it, but found an online video how-to and had it reassembled in less than an hour with most of the time spent removing the metal pin that secures the gear on the drive stem and cleaning parts. The new gear did not come with lubricant so I used smeared a generous amount of white Li-grease on the worm gear and the drive gear. I spent nearly as much time adjusting the up and down movement screws on the side of the drive. Drive is working perfectly. Hopefully, I will get another 10 years use.

Exactly what I expected, but not an easy replacement. Not for the novice homeowner

This original piece failed (deteriorated) in my old Liftmaster and this replacement part fit perfectly.

Never showed up when it was supposed to, the only reason I paid for prime was to get stuff in a timely manner, Amazon is starting to suck, but the gear fit perfectly