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Garage door opener chain has jumped on the sprocket and jammed

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Working on a garage door opener with the power connected is a very dangerious undertaking, unplug it first.

Pull the plug, and release the door. Release the tension on the chain and you should be able to straighten the chain. Re-install the chain and re-tension it. If the sprocket is to wore out you will need to replace that or the door opener. Plug in the power and connect the door. Test it you should be all set.

Posted on Apr 29, 2014


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Posted on Jan 02, 2017

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SOURCE: Garage door opener chain out of sync with door

There are two white screws on the sides that adjust the limits. Adjust the "down" screw less. You should have to turn the screw 4 full turns for eight inches. After you make this adjustment, test it without the door being hooked up to prevent damage to the door or opener if it tries to close too far.

Posted on Mar 01, 2009

  • 547 Answers

SOURCE: how do you shorten the chain on a garage door

find the link and remove as much as needed replace the link.

Posted on Jun 19, 2009

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Posted on Jan 12, 2010

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SOURCE: Liftmaster 1/2 HP Garage Door opener won't open or Close

The shaft on these garage door motors are not direct drive systems. You'll have to open up the box to see what the actual problem is. I have had stuff like this happen where a gear just slipped out of place.

Here is a link for a parts supplier. I don't know your model but it looks like most of the Liftmaster worm screw gears and drive gears are plastic so it's possible that one of them has cracked.

Posted on Feb 14, 2010

  • 504 Answers

SOURCE: Stanley garage door opener chain screw adjustment


Posted on May 26, 2010

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Garage door opener

Does the travel direction make a difference? There is typically upward / downward force adjustments. Also when it stops will it start again immediately if you activate it.

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My Craftsman garage door opener is not working - I opened the inside of the opener and motor is humming but gears are like jammed....when I prod the gears with a screw driver they do spin for about 3...

I had the same problem. In my case the bushing for the main drive gear was worn out. This is just below the sprocket that connects to the chain.
What you should do is remove the chain and see if that sprocket shaft is loose in the bushing. The motor should turn without the chain on.
If this is the case check the plastic gears within the case. If there all chewed up and the bushing is shot you most likely need to replace the unit. If the gear's are still good you can replace the bushing.
I'm not sure how much Sears would charge to rebuild it but it is very possible it would be cheeper then buying a new one

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The chain came off my Craftsman 53920 garage door opener. How can I fix this problem?

When a chain comes off it is an indication of another problem. The bearing on the sprocket shaft is bad and lets the sprocket lean forward and the chain pops off. The part number you need is 41C4220A Gear and Sprocket Assembly. The chain can be loosened by the nuts on the trolley.

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

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My garage door chain came off, i put it back on

Loosen the chain enough so that you can remove it from the sprocket above the motor unit. With the door closed run the motor until the sprocket turns clockwise and stops. With everything attached replace and tighten the chain. Some adjusting of the up and down limits will probably be required.

The chain normally comes off when there is a problem with the sprocket and gear assembly. The bearing goes bad and lets the shaft lean towards the door and the chain comes off. If this happens again you will need to replace that assembly which is part #41C4220A and is available at any good door service company.

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How do I tighten sagging garage door chain?

I think you have more problems than just a sagging chain. It is most likely sagging because the bronze bushing at the gear and sprocket assembly is bad. It lets the sprocket lean forward and loosens the chain. You will also need to remove the cover from the motor unit and check the drive gear. It is a white gear just in front of the motor and is most likely stripped.

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Garage door will not open

You can fix this by loosening the chain enough that you can lift it off the sprocket. Then run the opener until the sprocket turns counterclockwise and stops. Now with the door in the open position replace the chain. This will get the chain running the right direction. You will have to adjust the open and close limits along with the force adjustments but that will all be covered in your owners manual.

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Loosen the chain enough that you can remove it from the sprocket. Run the opener until the sprocket turns counterclockwise and stops. With the door in the open position replace the chain. You will probably need to adjust your open and close limits per your owners manual.

May 23, 2009 | Sears Craftsman LiftMaster Chamberlain...

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Craftsman opener motor works, but chain does not move.

If the motor is working but the chain does not move you must remove the cover on the motor and check to see that the chain is on the sprocket. If the chain is on the sprocket and the sprocket is not moving but the motor shaft is moving then the sprocket must be retightened onto the motor shaft.

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

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