TWO EMPLOYEES WERE ATTEMPTING TO REMOVE THE PIN FROM THE COOLER DRUM CHAIN. THE INJURED EE WAS HOLDING A LARGE SLEDGE HAMMER IN PLACE AGAINST THE CHAIN, WHILE THE OTHER EE USED A SMALL 2 LB HAMMER AND A PUNCH TO TRY TO KNOCK OUT THE PIN. THE SMALL HAMMER MISSED THE PUNCH, STRUCK THE INJURED'S LEFT THUMB, SMASHING IT BETWEEN THE SMALL HAMMER AND LARGE HAMMER HANDLE.