Question about Sears Craftsman LiftMaster Chamberlain Garage Door Opener Wireless Keypad Model 976LM Security+

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Garage door only opens 4 inches then reverses and stops

Hi, my garage door opener plastic gear wore out. I bought the kit and replaced the gear and worm drive. The motor runs fine, but the door will only close 4 inches before it reverses backward 4 inches from original starting position. I've played with adjusting the up down limits until the cows came home.....but just keeps doing it. Is it time to toss it or is it something that can be fixed? It's a 1/3 HP. Thanks very much.

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You need to replace gear when the door is fully closed. then do your tweaking.

Posted on Jun 01, 2009

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With my door closed, i push door button to open and the chain and opener continues inthe closing mode. any help?


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Jan 10, 2016 | Sears Craftsman LiftMaster Chamberlain...

1 Answer

1/2 hp craftsman door opener moves about 12 inches then reverses back & thats all it will do. just replaced the main two plastic drive gears whenthis started


First try adjusting the force limits. They are up on the motor head. If this works do a 2x4 safety reversal test afterward. It also may be the rpm sensor. Sometimes this can go out with the gears. There is an led light on the motor head. If it is flashing 5 times in a row then it is this for sure. You can get replacement parts at searspartsdirect.com. Thanks BB

Sep 19, 2010 | Sears Craftsman LiftMaster Chamberlain...

3 Answers

Motor runs but door does not open


you have a stripped gear on your opener. Replace gear and sprocket kit

Feb 01, 2009 | Sears Craftsman LiftMaster Chamberlain...

2 Answers

Lift master garage door opener. Motor makes noise when switch is hit likes its running but chain/sprocket doesn't move and the door is stuck open. Chain is on sprocket. Not sure if the motor is frozen? ...


I had the same problem. Took the cover off of the opener and found that the gears were stripped on the unit. Motor was fine. You can order gear replacement kit for the unit. They are a plastic type sprocket and worm gears. The kit comes with spindles and all necessary clips. You have to take the unit off the ceiling to replace the gears, but the process if very easy to do. Parts kit about $40 on line, much cheaper than a new door opener. Total process took less than 2 hours, including getting the unit down and back up again.

Jan 24, 2009 | Sears Craftsman LiftMaster Chamberlain...

1 Answer

Opener goes 12"+/- and then returns


havent heard any of yu say you adjusted the down force.

Jan 21, 2009 | Sears Craftsman LiftMaster Chamberlain...

1 Answer

I have a Craftsman garage door opener and just replaced the plastic gears. I followed the step by step directions but the door is now only opening 2-3 inches, reversing and then going back down. any ideas?


I managed to troubleshoot this myself and got my door working. The problem was that the black rpm wheel was not far enough down on the gear shaft. By unscrewing the screws on the final piece of the assembly on the shaft and then pushing it all more firmly toward the motor and rescrewing in place, I made it so the door operates beautifully.

Jan 06, 2009 | Sears Craftsman LiftMaster Chamberlain...

1 Answer

Garage door will not work


Check to see if you plugged in the 4 wire limit assy. harness.

Dec 16, 2008 | liftmaster Chamberlain Garage Door Opener...

1 Answer

Garage opener cannot close, just replaced gears.


If the unit has photo eyes that could be your problem. not reattching the 4 wireing harness from the limit assy. can cause a similar issue.

Dec 13, 2008 | Chamberlain Powerdrive PD422D 1/2 HP...

2 Answers

Garage door won't close.


After replacing the worm gear and main drive gear on my Craftsman 1/2 HP garage door opener I found that my door moved about 4 inches stopped and reversed the same distance. I checked all the settings and everything seems OK. What fixed the problem was I released the two allen set screws on the end of the motor shaft and pulled tha motor shaft toward me. When I replaced the black plastic cap that looks like a pill cap top on the end of the shaft this corrected the depth setting that cap rotated through the RPM sensor. I set the limit settings (up and down) on the side of the opener and reset the force pots marked (KC) to mid range.
the door now works. I hope this helps. I also checked and eliminated the door sensors by putting a box in the beem this inhibited any movemnet at all, so I knew it wasn't the door sensors as there was at least 4 incheds of movement prior to the box and nothing with the box.

Oct 27, 2008 | Sears Craftsman LiftMaster Chamberlain...

2 Answers

Lift master 1265lm 1993


check and see if a spring is broke on either side above the door in the middle. (big springs) that's my problem.

Aug 30, 2008 | Sears Craftsman LiftMaster Chamberlain...

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