Manufacturer and model number of your garage door.
Garage door opener sprocket broke off.
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Over time the sprocket s teeth can wear and the chain may jump or skip when the opener raises the door.
Chain drive garage door openers have a sprocket that is attached at the top of the motor.
Chain driven garage door openers should have some slack in the chain for optimal performance.
You can put the chain back on your automatic garage door opener using a simple adjustment mechanism.
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Operator brackets come in different styles some are.
Over time though this slack can increase or the gear and sprocket assembly can wear and the chain may pop off the sprockets.
A new front sprocket costs about 150 200 include the labor to install it.
If the piece of metal that broke off is the piece where the j bar that connects your garage door opener to the door then you can repair this by installing a new operator bracket.
If you are not confident in your ability to diagnose the problem call a local garage door service company.
The chain wraps around this sprocket as well as the gear and sprocket at the motor.