Stripped gears Liftmaster 1255


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Old 03-22-13, 02:48 PM
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Stripped gears Liftmaster 1255

Upon pressing garage door button the motor begins to spin, but does not engage the gear that drives the chain.

The inside of the unit is covered in a fine white plastic coating I've seen referred to as "plastic snow."

My conclusion is that the gear is stripped.

I am asking for advice on whether or not I should replace the entire unit or replace the stripped gears.

Any advice would be much appreciated.

Thanks in advance.

 
  #2  
Old 03-22-13, 02:51 PM
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This website has a huge selection of parts:
Liftmaster Chain Drive models 1255, 1255R, 1256, 1256R, 1260, 1260LK, 1265 Parts

Suggestions?
 
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Old 03-22-13, 04:39 PM
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just replace the gears. the units never die. be sure to use all the brass bushings in the kit.
 
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Old 04-08-13, 01:21 AM
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So I did this. Got everything working. Then... Well....

I forgot to ensure the next push of the switch would bring the door up. So when I finished everything and pushed the button it sent the garage door down. Now the chassi is right up against the end of the rail, and one said of the chain is in tension while the other side is completely slack.

It looks unsafe right now. Is there anything I can do short of calling a professional?
 
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Old 04-08-13, 09:26 AM
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yes.

remove the motor case and rotate the motor by hand. power off of course.
 
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Old 04-08-13, 01:49 PM
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Any advice for rotating the motor by hand?
 
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Old 04-08-13, 04:58 PM
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you might have to download the pic to read the text. should be a good jumping off point.
 
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Old 04-08-13, 05:22 PM
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Wouldn't it be easier to just remove the chain, run the motor to the up or down limit, then re-install the chain?
 
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Old 04-08-13, 05:38 PM
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"Wouldn't it be easier to just remove the chain, run the motor to the up or down limit, then re-install the chain?

not in my opinion. at the most the chain/carriage is moved 5". adjusting the limits will be done with the with the limit assembly its self.

"one side of the chain is in tension while the other side is completely slack.

a lot of work goes into removing an OP chain thats tight as a drum. turning the motor shaft is just releasing the tension.
 
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Old 04-08-13, 06:12 PM
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Ok...I might have misunderstood the issue....thanks!.
 
  #11  
Old 04-14-13, 10:54 PM
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Easy fix here

on the bottom of the gear and sprocket assembly shaft is a little gear that you put on that is held in place with a little 3 prong clip. This little gear moves the limit switch to the open and closed limit. Take this little gear off then rotate the gear that it meets with when assembled until the limit switch is touching down limit contact. Put the little gear back on and run it. The limits are going to be messed up and the door will not go all the way open at this point. If possible (depending on where the limit contacts are) adjust the up limit up to where you want it but first adjust the down limit up a bunch of full turns, Probably around 5 or so then tweak everything from there. I hope this helps. let me know how it turns out.
 
 

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