Craftsman Garage Door Opener Not Closing
I have a Craftsman garage door opener Model# 139.53677SRT3 that is not closing all the time. It will open all the time but after it has been in the open position for a while it will only travel down about 12" and then reverse and come back up. The sensors are aligned properly and there is no obstruction. The lights remain green during operation. The gears are functioning correctly with nothing interferring with their operation. I have adjusted the down limit adjustment and that is not the problem. There is no problem I see when looking at the door and the track. Any ideas as to why the door does not close all the time?