Jammed Up 1/2 HP LiftMaster 41A5371-3


Old 08-06-19, 12:00 AM
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Angry Jammed Up 1/2 HP LiftMaster 41A5371-3

Yesterday I raised the single garage door that is attached to the above opener and it raised very quiet as usual. After about 15 minutes I pressed my remote and there was a slight grown followed by another grown that sounded like it was rebounding to the original position. I pulled the release and the door was easily closed with one hand.

I researched YouTube but found nothing that worked for me. I did unplug the power and waited about 5 minutes and plugged it back in but the chain still made the same noises and the lights never flashed. I also tried the wall button with the same results.

Today I performed a closer inspection of the 1/2 hp unit and saw that there was some slack in the chain on the trolley. I inspected the gear on top of the opener and it was intact. I then checked the chain on the opposite side of the trolley where the tension adjuster is located and I found the chain to be hard as a rock without any droop in this side of the trolley. I thought this odd and expected the chain on both sides of the trolley to have a similar droop.

Is there a sprocket at the other end of the trolley where it attaches to the wall that could have frozen in that short amount of time? I may be wrong but I believe the tight chain “stop” may have jammed up the mechanics and be part of the problem.

Thanks in advance for your help.

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Old 08-06-19, 04:49 AM
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My guess is the chain has the same tension on both sides of the drive sprocket with the motor off. With the door going up/down (motor on) one side of the chain will have more tension than the other side.Yes, there is a chain sprocket on the door end of the track, It usually is an open bearing type than easily can get jammed. You can check the chain sprocket bearing on the door end by removing sprocket. You first have to release tension on the chain. Be careful not to move the chain much as this will change the opener's up/down position relative to the door's position.
Old 08-07-19, 04:21 AM
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Check the trolley, I would bet it is jammed against the 5/16 stop bolt.... loosen the chain, push button and run the opener towards the closed position then immediately unplug the opener to stop it. Tighten the chain back up and then adjust the open limit so it cannot go up that high again
Old 08-07-19, 10:26 PM
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Thanks guys! I am going to jump on this first thing in the morning 😏.

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