My Craftsman garage door motor is not turning the chain. Rule Out the Opener. sears garagedoor opener sprocket will not turn when I push the button . Close the garage door manually, if it's not already closed. December 26th, 2008. There’s something wrong with the garage door opener, that’s stopping it from opening the door for you. As the drive shaft and sprocket rotate, they drive the trolley that lifts and lowers the garage door. The plastic gear on the drive shaft is designed to fail if the garage door gets stuck in the travel tracks, protecting the expensive drive motor from damage. If the motor is turning but the sprocket is not, you have a striped drive gear or the set screw has striped or backed out allowing the sprocket to spin. Get shopping advice from experts, friends and the community! In most cases, the cause will be a stripped gear or a chain that has come off the sprocket. A professional garage door technician will be able to tell you whether it is best to replace the opener or repair the old one. Initially the door would move a few feet then stop, forward or reverse, motor continuing to run. Replace the gear shaft and sprocket assembly if it's damaged or worn out. Sears 1/2 horspower garagedoor opener. Report This by Manage My Life. Report This by Manage My Life. What has failed when the door opener motor runs but the sprocket is not turning? September 8th, 2009. I have a 1/2hp Craftsman garage door opener model #139.53625. On many units, the sprocket spins clockwise (when viewed from above) to close the door, but this operation varies by model. If you are able to raise your garage door easily, it is not the problem. Step 2 Press the wall control button or remote so that the opener completes its CLOSE cycle, and the sprocket on the top of the motor unit stops spinning. So you’ve made all these checks, but it’s not your garage door that’s causing the problems. I took the chain off to see what was stuck and it does the same thing. You will need to take the opener apart and replace it or have a repairman do it. If the gear is worn or damaged, the door won't move properly. is 139.53637SRT1. I do not see the sprocket on top turning either, though the motor is running through the up and down cycle. I have not removed the casing yet to look at it. It will probably be cheaper to replace the whole opener by the time you buy the gear and have it repaired. I have been manually operating the door for some time, probably for over a year. The model No. This indicates that something in the opener system has malfunctioned. I push the remote and the sprocket that moves the chain acts as if it is stuck ... makes a noise and moves a 1/4 inch or so.