I'm gonna take a guess here, but it sound like your neutral safety is jammed (or was) in the safe/no move mode via that that seat brake lever. The clicking you hear should be some hefty relays that send power to the motor. How old is this thing? I'm guessing it could be pretty old as it reminds me of a Yale that I worked on eons ago with a similar setup (relay bank to the right of drivers calf and park brake/travel lockout via the seat.