Sears craftsman garage door opener 139655000 moves about 12" and returns seems to be only with load of door on it. If I disconnect the door the the drive will travel down engage door and reopen. I don't have a manual for it.

Hi, I gotta tell ya this is an old opener and there is not much info on it. I will give you the basics. If your door is equipped with safety sensors (the little boxes on the bottom of the rails that keep the door from closing on something) you need to make sure there are no obstructions,( its a light beam) the wires are intact and that they are aligned and clean. There is usually a light on one of them to indicate it is working. If this is the problem you can let me know if you need more help. If you aren't sure, the door movement can be checked by bridging out the sensors. The other thing is this door has the copper arm type limiters and if the cover was removed it is easy to pop off one of the arms, you can check this but don't if you didn't have the cover off. Good Luck!