EE HAD A COMEALONG HOOKED TO A PIECE OF METAL IN SOUTH DEBRI SUCTION PIPE. OTHER EMPLOYEE PUT TENSION ON COMEALONG TO REMOVE METAL. WITH TENSION ON COMEALONG, INJURED EMPLOYEE TRIED TO FREE UP THE METAL IN THE SUCTION, BY HITTING IT WITH A PIECE OF FLAT BAR. WHEN HE HIT THE METAL, THE HOOK SLIPPED OFF OF THE METAL PIECE & STRUCK EE ON THE LEFT SIDE OF MOUTH.