I just got one off ebay so I havent recieved it yet but here is what the seller told me about it.
"Do you know how a rear hub on a bicycle works? The turret works in a similar way, in that it makes use of pawls. You have six pawls, each 60 degrees apart. Originally there was a 12vDC motor on there. One would supply 12v to the motor, and the turret would rotate. It would rotate the turret until it has completely passed the pawl. Then, the polarity of the voltage is reversed, and the voltage being supplied is cut in half. THis makes the motor rotate the other direction, backing the turret against the pawl. The motor doesn't cook because it is being supplied with only a few volts. I think it's a pretty clever arrangement myself, and leaves no room for positioning error. The turret is rotated via worm gear already, so it's pretty rigid to begin with. I think a step motor is better suited for the job because it doesn't require any extra circuitry (other than your typical stepper drive). "
obviously Im going use a stepper motor instead of a dc motor.
Is that any help.