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

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Craftsman GDO, Model 139.53600. moves 4inches up/ down

I had to replace the main drive gear and now the door will only move 3-4 inches and then reverses from either position. It is currently open inthe up position. I have adjusted the limit up and limit down switches to allow for plenty of movement. I have adjusted the Force up/dn. Neither worked.

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Find the increase travel adjustment screw and turn it clockwise 1/4 to 1/2 turn.

Posted on Jan 14, 2009

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Craftsman 139.53600 I had to replace the main drive gear and now the door will only move 3-4 inches and then reverses from either position. I have adjusted the limit up and limit down switches to allow...


Make sure you put the black cup back on the end of the motor shaft and that it is pressed all the way on. Make sure the RPM sensor is plugged in. If neither of these are the issue, then you probably did not have the motor shaft pushed all the way back when you tightened the coupler after replacing the worm gear. Loosen that coupler up and from the front of the motor (opposite end in which the coupler is on) push the shaft back as far as it will go. Hold it there while you tighten the coupler back up and then try it.

Apr 04, 2011 | Sears Craftsman LiftMaster Chamberlain...

1 Answer

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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...

1 Answer

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Apr 02, 2010 | Sears Craftsman LiftMaster Chamberlain...

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Feb 21, 2010 | Sears Craftsman LiftMaster Chamberlain...

1 Answer

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1 Answer

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1 Answer

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Nov 14, 2009 | Sears Craftsman LiftMaster Chamberlain...

2 Answers

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