I agree with beelzeboob. Like I said in your other thread on this, it's the sector gear that helps limit the movement and direction. Also, if I remember correctly, there's a control board for the motor under the playfield. Somehow, (I assume through magic) the windings in the motor change polarity or phase or magnetic feilds depending on the current and moving the rotor, etc. etc.
Just hook up the jaw linkage to the gear, button Rudy back up and have at it. If you are worried, buy an extra set of gears or the metal ones if you can find them.