We have an automatic garage/overhead door that has suddenly stopped functioning properly. There is a "release rope" with a handle that hangs down a few feet and when I pull that, the door opens and closes just fine without any issues. However when I click the button to engage the Operator/Opener (Craftsman 1/2 HP) it makes a noise and attempts to engage something for a few seconds, and then gives up.

Here are some photos: enter image description here enter image description here

And here is a YouTube video I uploaded to demonstrate exactly what's happening.

As you can see in the video the door arm is very loose and so I wonder if something broke off, sheared or came loose? How can I troubleshoot or diagnose what the problem is? Objective is (obviously) to get the automatic opener working again. Thanks in advance!


FWIW several members have suggested it could be the "drive gear" inside the Craftsman operator/opener housing. I found a video that allegedly shows how to remove and replace it and here is what the video author says is the drive gear:

enter image description here

With Amazon link here.

  • 1
    Looks like there should be a gear attached to the motor. Good chance it is attached to the motor with a shear pin that is now broken. The motor shaft is now just spinning without turning the gear. The manual should mention the proper shear pin replacement. Could also be a machine key that has sheared.
    – crip659
    Mar 22, 2022 at 14:28
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    I have two similar openers, one very old and one pretty new. Both exhibit the same looseness of the door arm. I wouldn't worry about that issue. Mar 22, 2022 at 14:38
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    I agree it could be a shear pin but several that I have been called to work on had drive belts that broke, the good thing is it is trying , when they just click or no motor noise it has been much worse in my experience.
    – Ed Beal
    Mar 22, 2022 at 14:49
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    I installed a Sears opener in 1996. After about 15 years of service, the main/final drive gear that turned the chain had all teeth sheared off. It was a plastic gear. So the motor ran but the chain sprocket did not turn. Mar 22, 2022 at 15:03
  • If the gear was stripped or broken, I think the motor would run for a wile. Check the optical safety sensor to make sure it isn't dirty or blocked. Mar 23, 2022 at 4:50

2 Answers 2


I had a Craftsman garage door opener as the original I installed in my garage. After about 20 years (give or take a bit, I don't recall exactly), I had essentially the same thing happen.

I took the opener down and looked inside. The plastic drive gear between the motor and the chain drive had lost some or most of its teeth. The motor ran (that's the buzzing noise you hear) but the motion wasn't being transferred to the chain.

I bought a replacement gear (this was long enough ago that I walked into my local Sears store and ordered a replacement - good luck with that today), installed it and all was good. Unfortunately, a few months later the motor itself died. I decided it was time for a replacement with a whole new unit.

If you can get a replacement gear, give it a try. Depending on the age of the opener, though, you may be better off just replacing the whole thing.

BTW- The trolley is supposed to be loose on the track. Maybe not quite that loose, but I really don't think that's going to be a problem for you. Obviously, it was working fine a couple of days ago, and I find it hard to believe that the plastic slides inside it have totally and completely broken down, especially since you can open & close the door by hand with no issues.

  • Replacement gear probably does not need to be from the maker or plastic. If you know shaft diameter, number of teeth and pitch of the gear there should be replacements available. Farm machinery dealers usually have a selection where you can mix and match gears and collars to fit on shafts.
    – crip659
    Mar 22, 2022 at 15:26
  • Good idea, @crip659. Plus, if you can get it in metal instead of plastic...
    – FreeMan
    Mar 22, 2022 at 16:10
  • Thanks @FreeMan (+1) - I found this video after googling "craftsman garage door opener plastic drive gear". Does this video reproduce (essentially) what the fix was in your case? Mar 22, 2022 at 18:50
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    I gotta be honest, @hotmeatballsoup. I got as far as seeing the floor joist cut 3/4 the way through to make room for the opener (and saw the split coming from that cut) and immediately discredit any and everything this guy says or does. That is NOT the way to make room for your garage door opener. TBH, I didn't watch beyond that.
    – FreeMan
    Mar 22, 2022 at 22:31
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    @hotmeatballsoup that looks a lot like I recall my drive gear looking when I opened it up. I would suspect this is the problem with yours as well, but the only way to know for sure is to open your drive unit up. It's really not difficult or scary. ;) It might have to sit on the bench for a couple of days while you get replacement parts, but it's not doing any less to open the garage door there than it is installed on the ceiling, so tear into it.
    – FreeMan
    Mar 23, 2022 at 11:18

Probably not the case, but when I had to replace my cable, I managed to wind up with the truck in a retracted position while the garage door opener thought the door was closed, which resulted in a similar sort of behavior as it tried to open the door further, but could not because the door was already at the open position and couldn't go any further. I think that this was only possible because I had replaced the cable, and therefore taken up slack, but it might be worth checking to see if the cable is already taut, and trying to pull tauter.

  • Thanks @Sean Duggan (+1) I will check for that as well. Mar 22, 2022 at 19:57

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