As you look at the treads the motors are controled by a circuit board, I suspect that it has gone bad, These motors and the componets get all kinds of gunk/water in them. I helped ChevyFanGermany tear his apart and found they were completly rusted fast.
As you see in the attached pics, You can follow the wires back down from the motor, to the connector. Your wires may be a different color depending on model/year. But you should be able to directly jump it with a 9 volt battery or even a old car batt, just to be safe. Plug the wires into the connector and just swap them/reverse them. This will change the polarity and make the motor working it in and out. The little control board inside the motor has limit stops in it and controls it from going to far out or in. I don't think it is a fuse, You said it does fold in but not out. Tends to sound like the control board or switch.
Sam