EMPLOYEE AND 3 COWORKERS WERE SPLICING THE 3A BELT WHICH HAD A SPLIT. WHILE INSTALLING A 12 FT PIECE OF BELT, THE WIRE ROPE USED TO SHEAVE THE BELT SLIPPED FROM THE SINGLE CROSBY CLAMP, WHICH CAUSED THE BELT TO LOSE TENSION. THE COME-A-LONGS JERKED TO THE SIDE STRIKING INJURED IN THE STOMACH. WHILE CHECKING THE SCISSORS USED TO HOLD THE BELT CLAMP CAME LOOSE AND STRUCK SHOULDER.