You might be overthinking this one. I just finished putting my FH back together, and the one thing I got right (after lots of tinkering and bothering people with questions) was the Rudy rebuild. I just put the motor back on the gears, and when I put the jaw back on, I just pushed it all the way up so his mouth was closed. When the motor fires up, it pulls the jaw down level with the PF, then puts it right back where it belongs. Must be the gears that control the stopping and reversing. I don't really care...as long as it works!