garage door opener
Craftsman model 139.53985DM
Has been working for a year or two. Now it opens okay but when closing will travel only part way before reversing. Occasionally will close properly. The safety sensors are lighted and steady as this is going on. Disconnected the door moves freely pushing or pulling from top or bottom and is properly balanced. When closer is activated with door disconnected it still reverses after partial travel most of the time.