This was a craftsman model 139 53976srt.
Garage door sprocket broke off.
It was a perfect replacement and the garage door is working.
Chain driven garage door openers should have some slack in the chain for optimal performance.
The chain wraps around this sprocket as well as the gear and sprocket at the motor.
This sprocket is typically used on a soled keyed garage door shaft.
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.
This gives the appearance of a broken chain or belt.
If the gear and sprocket assembly breaks the motor runs but the door won t move.
Chain drive garage door openers have a sprocket that is attached at the top of the motor.
This diy repair guide explains how to replace the gear and sprocket assembly on a chain drive garage door opener.
This gear set worked great and replaced a broken one in my 2002 1 2 hp chamberlain liftmaster yesterday.
This is the part that connects the motor to the chain or belt.
Located at the top of the motor unit the gear and sprocket assembly drives the chain that opens and closes the garage door.
Sprocket is at the end of the opener rail closest to the garage door opening.
A new front sprocket costs about 150 200 include the labor to install it.
We carry many other garage door sprockets several for various brands and models of garage door opener sprockets.
You can put the chain back on your automatic garage door opener using a simple adjustment mechanism.
Sometimes it was taking several tries sometimes it was going fine the first time.
This is a video on how to change the gear sprockets in a craftsman garage door opener.
Garage opener sprocket broke off i already had problems as the door would move a little trying to close then back open.
Over time the sprocket s teeth can wear and the chain may jump or skip when the opener raises the door.
The bag said it was an oem piece.
After several years the garage door springs become weaker causing more stress on.
If you are not confident in your ability to diagnose the problem call a local garage door service company.
Over time though this slack can increase or the gear and sprocket assembly can wear and the chain may pop off the sprockets.
Eventually this will cause the sprocket to snap off.