I would start by checking all the microswitches on the joystick, then I would check all the microswitches up in the carriage assembly.
The switches on the joystick obviously are what tells it what direction to move in.
(left, right, forward, back)
The switches in the carriage tells it where the claw is.
There should be a switch where the claw goes up and down that tells it when it is in the "up" position, this will then send the whole carriage to the "home" position.
Start there.......