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

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Have broken the drive gear twice Chamberlain garage door opener

I replaced the drive gear last year and now it is broken again. I noticed the door was raising very hard a couple of months ago and that the rollers on the door were sticking so I greased them. Not sure if the door raising is what caused the drive gear to break or not. Any ideas of other things to check?

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There are two main reasons for the drive gear to strip the teeth. The first and most often cause is a heavy door. With a door opener we never lift the door manually so we don't know how heavy it is getting when it needs maintenance. The second cause is what may be your problem and that is lack of lubricant. In the gear kit there is a tube of grease that should be used on the gear. You just can't use too much. You may need new door springs.

Posted on Aug 16, 2009

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1 Answer

My Chamberlain Liftmaster Formula 1 garage door opener just started going up 2 inches then stopping. If I hit either the inside wall mount or the remote in the car it just goes back down 2 inches and back...


You need to check the door springs to see if one is broken and also remove the cover from the motor unit and check the drive gear. The gear is white nylon and will be very obvious if it is bad. The part number is 41A2817 and is available at any good door service company. It will come with instructions.

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Check the door springs. May have a broken one. Also remove the cover and look at the drive gear. It is white nylon and is just in front of the motor. It could be stripped.

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1 Answer

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how handy are you. can anyone do is a silly question. a blind person with no hands could not do. you need a socket set, hammer,screwdriver/allen wrench. kit costs $25-30 dollors. Gears will last as long as originals, not one year. It will take you 2-3 hours for a first timer. Takes me 30 minutes to rebuild unit once I take down and 20-30 minutes to reinstall, if you can change a washer or install a faucet, you can do it. what do you lose vs. what can you save.

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