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

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With the door disconnected, the chain moves about a foot then stops, the light flashes, and the chain moves back to its starting position.

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If the main light flashes 10 times when the door reverses to the open position it is a door sensor problem. Make sure they are pointed at one another and the small light on each is lit and not flickering. If tweaking them a bit doesn't correct the situation you could have a bad sensor.

Posted on Oct 07, 2009

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I have a craftsman garage door opener 1999. it goes two feet and then back down. I can open door with one hand. all gears are new as i rebuilt it (Twice).

Your "timing" is off. Disconnect the door from the trolley and tie down the door latch assembly so it does not engage the trolley. Then using the up down button on opener open or stop the trolley at the closest position you can to the motor assembly. Then open the door to the position it would be when open and note where the latch is at that point. Then loosen the drive and move the trolley to the position noted in former step.- then tighten the chain.
Now hook up the door latch to the relocated trolley and play with the up/down adjustments till you get it right.

Jun 11, 2017 | Building Materials

1 Answer

We just replaced the "trolley" component of the opener, now when we open the garage door it opens about a foot, then stops like its hung on something... it will go back down. If i help it pass the hun

Check your manual and re-program the up/stop and down/stop position. Also make sure the new trolly is in it's proper position.(in the closed position) Hope this helps

Oct 02, 2012 | Chamberlain 3/4-HP Power Drive Chain Drive...

1 Answer

Lift master 1/2 hp door not closing...moves a foot and then stops and goes back...eyes are good, both lights solid...have messed with the force to see if that helps...and nothing...light on opener itself...

check for a break in one of the wires that goes to the safety door stop sensors at each side of the door, the only thing that stops the door after a foot of progress is those sensors, and they can be off line quite a bit before being mis aligned , this question was listed under chain saws,, so if you could give me the make and model of your door opener I could help you more ,, just reply to this reply

Sep 08, 2011 | Garden

1 Answer

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 two craftsman door openers. They work great with pushbutton on wall, open and close ok. The door opens fine with remotes ( one handheld other homelink in car ) but will not close with remote. It...

If the main light flashes 10 times and the door reverses to the open position it is a door sensor problem. Make sure the lights on the sensors are both on and not flickering. Tweak them if necessary. If you cannot get both lights to come on you have bad sensors or the wiring to them.

Dec 27, 2010 | Sears Craftsman LiftMaster Chamberlain...

2 Answers

My older Craftsman garage door opener comes down about 6" & then goes back up. I just replaced all the rollers o& the opener worked fine. Then I tightened the chain on the opener & it worked ok...

If the main light flashes 10 times when the door goes back up it is a door sensor problem. You chain should sag just a little. If you tighten it too much it will click as it goes over the sprocket. You can increase the down force which is an adjustment near where all those white wires go. A 1/4 turn should be enough. Release the door from the opener and operate it by hand. It should move freely and when you have the door approximately waist high it should stay put. Neither raising nor closing.

Jan 11, 2010 | Sears Craftsman LiftMaster Chamberlain...

1 Answer

Garage door opens 1 foot, then stops.

It sure sounds like you have a broken door spring. While you are at it remove the cover and take a good look at the drive gear. It is white nylon and is just in front of the motor. Might be stripped and unable to take the weight of the door.

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

1 Answer

Craftsman 1/2HP Door Opener won't stay closed

Loosen the chain and run the opener until the sprocket runs in the counter clockwise direction and stops. Now with the door in the open position replace the chain. This will get everything back into sync but I hope you remembered where all those controls were. You need to put them back in their original positions.

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

1 Answer

I have a craftsman garage door opener and the chain came off the track. I've put the chain back on the track wheel but i had to loosen the chain to do so. now, when the door closes the bar bows up and the...

The reason your door is opening again is because there is a limit switch that is not making contact at the appropriate time to tell the drive to stop closing the door. The chain drive motor is controlled by a circuit that is expecting to see a signal telling it that the door is closed. If it doesn't see this signal to stop at the appropriate time, it continues to drive the door down unless it sees a certain amount of back pressure, which then tells it to return the door to the up/open position. This is a built in safety feature for most garage door drives and is industry standard now due to children getting caught under them and being killed. You can try this yourself. Stick a 4 foot 2x4 vertically under the middle bottom of the door as it's coming down, after a second or two the door will reverse direction.

With the chain falling off the drive and loosening it to replace it, you may have inadvertantly positioned the actuator of the switch, which is usually attached to the chain, out of position by a couple of links. There is a momentary contact switch mounted close to the door on the support shaft of the drive mechanism. This support shaft is the one holding the motor drive on one end, along with the chain and is anchored to the header over the garage door. This momentary switch may have a short metalic or plastic arm hanging down that is moved by the actuator on the chain and needs to be reset to a position where the switch contact will be closed when the door is in it's closed position. There are other options also depending on how new/old your door drive is. Some of the newer models use a through beam sensor or photo eye as a stop switch.

Please let me know if this helps.


Dec 31, 2008 | Washing Machines

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