Garage Door Won't Close?

I have a Sears garage door opener that has elected to begin reversing for no apparent reason. It only runs down about a foot and reverses with the door disconnected and even with the chain OFF the drive sprocket. 1 foot and reverse. I have the obstruction lights taped eye to eye with the amber and green lights both lit. Still 1 foot and reverse.

I'm at a loss. I would just trash it but hate to toss it for a stupid reason.

Steve K