EE WAS HELPING OTHERS CHANGE ROLLERS ON A BELT LINE. EE WAS USING A METAL BAR TO PRY UP THE BELT FABRIC SO A ROLLER COULD BE REPLACED. HE WAS USING THE WEIGHT OF HIS BODY (CHEST) TO PUSH BAR D OWN. HE FELT PAIN IN THE LEFT SIDE OF HIS RIB CAGE. THERE WAS NO DAMAGE OR IMPAIRMENT TO THE OPERATION OR TO ANY EQUIPMENT. IMPROPER USE OF TOOL CAUSED INJURY. NO OTHER FACTORS WERE INVOLVED.