WHILE REPLACING MOTOR AND REDUCER ON CONVEYOR #971, THE INJURED PERSON HAD POSITIONED HIMSELF UNDER THE UNIT AND WAS REMOVING THE BOLTS THAT WERE HOLDING THE UNIT IN PLACE. WHEN THE LAST BOLT WAS REMOVED THE UNIT DROPPED APPROX. 16"" CRUSHING HIS LEFT RING FINGER BETWEEN THE MOTOR UNIT AND THE FLOOR.