EXPERIENCED PROBLEM AT 5PM BUT DID NOT HAPPEN AGAIN, MADE GUIDE CHECK FOUND DOG BRAKES. REPLACED NW DOG, NW DOG LINKAGE ARM (TOP) BOTH NW & SW LINKAGE ARMS (BOTTOM). REPLACED NW DOG MOUNTING BRACKET COMPLETE SHINED TOP WEST GUIDES 1/8"", OILED GUIDES ON CAGE AND COUNTER, WEIGHTS USED SLOPE HOIST TILL NOON 2/5/05.