I have a 1\2hp Craftsmans GDO. It's probably 25yrs old. Has worked great until it stuck in the open position. The wall switch and remote activate the internal GDO switch but the motor will not start. When I rotate the large pully inside the GDO manually - lifting white plastic ring off of the close limit switch - the garage door coupling on the rail moves about 5 inches away from the GDO - the motor starts and moves the GDO coupling on the rail back toward the GDO closing the door again. Weird huh? The door moves freely when disconnected from the GDO. I think there is something inside the GDO between the switch that gets the signal and the motor that is malfunctioning. If there is a $10 fix to this I hate to spend $150 on a new GDO. I know GDO's aren't made to last forever.