Garage Door Gear Replacement on LiftMaster Craftsman Openers - Broken Gear and Sprocket Replacement 

Garage Door Gear Replacement on LiftMaster Craftsman Openers - Broken Gear and Sprocket Replacement
Garage Door Replacement Gear and Sprocket Kit: amzn.to/3JSpj1A
Vice Grip: amzn.to/3qKsrW5
Recently my garage door stopped opening but the motor was still able to run. This is caused by a stripped out gear inside the motor housing. And in this video I'll show you step-by-step how to fix it yourself! On the front and back, only the bottom screws need to be taken out. But once the cover is off I see a pile of what looks like plastic shavings. This definitely shouldn't be there! On the other side, the main sprocket is completely shredded! There's practically no teeth left on this gear! So it needs to be replaced. I was able to easily find the part on Amazon for just under $20.
And I recommend buying the entire assembly like this rather than just the gear itself. Mainly because this part is easier to install with fewer steps. So start by disconnecting the door from the motor. And on the track the chain needs to be loosened. Use some vice grips to mark the trolley in it's current position. Now loosen and unscrew the nut closest to the garage door. The other nut on the motor side needs to stay in place so don't move that one. There's actually a lot of tension on the chain so it takes awhile before it's loose enough to use my fingers. But this nut needs to be twisted almost all the way to the end and it's not necessary to take it all the way off.
Now take off the cap on the chain sprocket and remove the chain. There are three screws that need to come out but they can only be accessed from inside the motor housing. However, I need to remove the small worm gear by first taking off the 3-prong retaining clip. With a 5/16 nutdriver, I'll take out two of the screws I can directly access with this tool. The third one is blocked by other components so the nutdriver won't work on that one. But you'll need a socket for the 3rd screw. Once I've taken out the last screw, the gear can be lifted out. Even though the replacement comes with lots of parts, I'm only going to use the sprocket assembly and grease.
Before installing the new part, remove the retaining clip and small gear on the bottom. One thing you need to know is that the three screw holes aren't threaded. So I'm going to use the existing screws and cut screw threads into the metal. When all three are done, take them back out. Now I'll apply a liberal amount of grease on the main gear. With the main sprocket greased up, I can insert it back into the motor housing.
Up on top, line up the screw holes and make sure the two rectangular openings face the front and back of the garage. I'll then reattach the small worm gear I removed earlier. And just to make things operate smoothly, I'll apply some grease on this gear as well! Ok now I'm going to start reassembling everything by putting the mounting screws back in. The first two screws are easy with my nutdriver but remember you'll need a socket for the 3rd screw.
Ok with the sprocket assembly secured, I can reattach the chain. When hooking the chain back up, I'm watching to make sure the trolley is against the vice grip before it goes over the gear. At this point, I can now tighten the nut that's closest to the garage door. Remember to leave the other nut in place. With this chain, I tried to keep it in the same position as it was when I removed it. But once I got it fully tightened, I the trolley was about an inch away from my vice grip. I don't think this is a problem because it should be close enough.
Now I'll plug the garage door opener back in and give it a test. At this point it's working great! I can now replace the cap over the chain gear and reconnect the door to the motor. Finish up by reattaching the cover on the motor and the repair is pretty much done! I've listed the replacement parts here in the description so it's easy for you to find! This is a moderate level DIY project. But I'd still say most of you should be able to do this and save some money. If this video was helpful please give me a thumbs up and hit the subscribe button to stay up to date on all my DIY repair videos!
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