THE #1 HOIST SERVICE BRAKE FAILED TO LOCK IN CAGE LOWER MODE AND TRAVELED THROUGH THE LIMIT SWITCH. PARK BRAKE ENGAGED AND STOPPED THE HOIST AT THE BOTTOM. THE HYDRAULIC CYLINDER WAS LEAKING A ND HAD FOREIGN MATERIAL BETWEEN THE PISTON & CYLINDER WALL. MINE EVACUATED, THE CONDITION REPAIRED AND THE HOIST WAS TESTED FOR PROPER OPERATION. THE MINE WAS RE-ENTERED ON 2/4/00 AT 10:45 AM