THE HOISTMAN WAS HOISTING A BUCKET OF MUCK. THE BUCKET HAD CLEARED THE CROSSHEAD AND WAS ON ITS WAY OUT OF HOLE. THERE WAS A LOUD POP & THE BUCKET STARTED GOING DOWN. THE OPERATOR WAS TRYING T O STOP THE BUCKET BY MOVING THE CONTROL LEVER IN & OUT OF THE NEUTRAL POSITION. THE FAILURE WAS ONE HYDRAULIC MOTOR TO BRAKE SPLINES. PARTS REPLACED 8-7-02 @ 2355 HOURS.