Liftmaster Model 1260. Manufactured 1993

My garage door worked just fine when I left for work this morning. Upon return it would not go up, just a few inches, stop, reveresed down and the motor continues to emit URRRRRRR... for about 30 seconds

I removed the motor cover and found that the flat gear driven from the motor gear has been chewed up. Is this normal wear and tear or should I be looking for the possibility that the door froze up because of a bad chain sprocket?
At first I was wondering if these gears are replacable but my opener has been in use for over 10 ten years so I'm thinking that I should replace the whole assembly.

Thanks for any info.

 

I would say contact LiftMaster at the link below.

http://www.liftmaster.com/cw/custome...=_1152,00.html