I have a 1/2 hp Craftsman Garage Opener less than a year old. Sometimes during the day the door will stop when going down. The hood light on the unit will flash 10 times. I have checked sensor connections, alignment, obstructions, door binding, down force, etc., with not luck. There is a green light on the back of the ceiling mounted base unit that flashes 4 times every minute or so. What does this mean? Are these error codes published somewhere? Any help would be appreciated. Thank you.