There is most likely a stray milling chip or some other type of debris that has caused the detent ball to stick in the turret ring. Usually the ball can be freed by alternately jetting WD-40 onto the ball and into the ball socket while pushing gently on the ball with a small tool like a small blade screw driver. Give this a try. If this does not work then you may have to send the turret ring to Lee for repair.
