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

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I replaced the drive gear and now when I turn on the openner the door goes up about 1 foot and then reverses and goes back down. Is this a problem with the limit sweeting or switch?

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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.

Posted on Apr 26, 2010

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I have replaced new gears and put back chain will only travel down 1 foot and back 1 foot light keeps flashing. Trying to get a full cycle?

When it only travels a short distance, and back up and the light flashes, that means that it's encountered too much resistance and the safety mechanism puts it in reverse and makes it go back up. This prevents children or pets from being crushed. Make sure that the gears are aligned and the chain is not getting hung up. There has to be some resistance causing the safety mechanism to go off. Also, if there is a safety Infra Red sensor hooked up to the system, make sure that it's wired correctly and free of obstruction. This can cause similar problems.

Mar 07, 2011 | Sears Craftsman LiftMaster Chamberlain...

1 Answer

I have a 1/2 HP Liftmaster Chamberlain Garage Door Openner that will neither open nor close now. I have disconnected the door from the carrier. With the carrier up, I press the button and it goes down...

1. Lubricate the chain and the shaft or angle iron that the carrier rides on.
2. If that doesn't work, see if the opener has adjustment screws for up force and down force. If so, try increase the down force about half a turn at a time.
Write back with your results.

Dec 18, 2010 | liftmaster Chamberlain Garage Door Opener...

1 Answer

Craftsman garage door had a stripped gear so I

if the stops are not wrong.
they tell it how far to go up and down.

then I think the safety sensor is misaligned.
make sure the light on one side is pointed at the receiver on the other. maybe it is dirty or blocked.

good luck!

Jan 10, 2010 | Sears Craftsman LiftMaster Chamberlain...

1 Answer

Craftsman Garage Door Opener Problems Going Down

It reversal of the door with the flashing lights is a normal function. It means that the door either didn't see the eye at the door bottom, or the force to close the door was to great. Both of these make the door reverse and go back up.
Just 2 months ago my spring broke. I had a guy out to replace and he found that the drive gear was almost broke off. I had tightened up the chain a month or two before this because it was sagging down far, and had noticed that it was sagging again when the spring broke.
So I had the gear replaced.
I'm guessing you have a similar problem. The drive gear is almost broke and the force to get the door down is too much so it reverses.
Gear cost was $119, so it was about 1/2 price of new opener.
But now with new spring and gear it's running quiter and slicker than I can ever remember it before.
Good luck!

Jan 08, 2010 | Sears Craftsman LiftMaster Chamberlain...

1 Answer

Worked great the past 2 years. Now, garage door

Remove the cover and take a look at the drive gear. It is white nylon and is just in front of the motor. Most likely stripped.

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

2 Answers

Garage door opens about one foot and remains there.

Check the door springs. You could have a broken spring. Also remove the cover and check the drive gear. It is a white nylon gear just in front of the motor. It is possibly stripped. This is a good time to release the door from the opener and operate it by hand to see just how heavy it has become.

Jun 29, 2009 | Sears Craftsman LiftMaster Chamberlain...

1 Answer

Genie garage door openner won't stop when it goes down or up

there should be a "travel distance" adjustment screw on the opener.

Apr 20, 2009 | Sears Craftsman LiftMaster Chamberlain...

2 Answers

Garage door opener will not work after gear replacement

From your description it sounds like you forgot to plug in the RPM sensor.

Mar 16, 2009 | Sears Craftsman LiftMaster Chamberlain...

1 Answer

Garage door opener will not work after gear replacement

check the end shaft platic cap is installed and runs freely between the rpm sensors.. that might be ur problem..

Mar 15, 2009 | Sears Craftsman LiftMaster Chamberlain...

2 Answers

Remote does not open or close garage door; inside button flashes

What has happened is that you electric eyes are blocked or have gone out. The eyes are at the garage door about a foot of the ground on both sides. There should be a red or green light on one of them. If not some thing is blocking the beam that goes across the door. It is a safety beam so kids can nt get hurt when the door is coming down. If the beam is broke the door will go back up.

Jan 24, 2009 | Chamberlain Powerdrive PD422D 1/2 HP...

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