WHILE EE WAS CLEANING SECONDARY PLANT C13 CONVEYOR, BELT WAS RUNNING OFF TO ONE SIDE; COUNTERWEIGHT ROLLER HAD MUD BUILDUP. EE TRIED TO CLEAN ROLLER PULLEY WITH A SMALL HOE; WHILE HOLDING ONTO HOE HIS LEFT HAND GOT CAUGHT IN THE PINCH-ROLLERCAUSING TRAUMATIC AVULSION TO HIS LEFT 3RD FINGERNAIL, MULTIPLE CONTUSION/BRUISES AND SMALL CUTSON LEFT FOREARM.