Most likely caused by a worn out gear inside the opener or a sheared off sprocket at the top.
Garage door opener sprocket sheared off.
Find the chamberlain garage door opener technical support you need to get your garage door opener operational.
It was a perfect replacement and the garage door is working.
When the garage door goes off track it can be a serious inconvenience.
Chain drive garage door openers have a sprocket that is attached at the top of the motor.
From informational videos to product manuals and troubleshooting articles the chamberlain group resource library has the information you need.
This is a video on how to change the gear sprockets in a craftsman garage door opener.
If the gear and sprocket assembly breaks the motor runs but the door won t move.
This can be replaced in about an hour.
If yours is a belt drive you need a kit like this https amzn to 2zqns.
Over time the sprocket s teeth can wear and the chain may jump or skip when the opener raises the door.
Https amzn to 2uwvnkj i m working on a chain drive opener.
This was a craftsman model 139 53976srt.
The replacement of this part is relatively straight forward and the instructions that come with the part part number 41c4220a are clear.
It wasn t listed for the same model but after looking online it seems that most garage door openers made after 1984 use the same sprocket assembly.
If you find that your garage door opener chain falls off the track on which it has been placed you will need to put it back up and then tighten the chain to stop this happening in the future.
This gear kit on amazon.
I had to replace the gear and sprocket assembly after the sprocket got sheared off likely due to too much play in the chain.
My door won t go up.
The motor runs but nothing happens.
The bag said it was an oem piece.
This diy repair guide explains how to replace the gear and sprocket assembly on a chain drive garage door opener.