EE WAS LOOSING A PLUG ON A GEAR BOX WHEN HIS HAND SLIPPED OFF OF HIS WRENCH AND HIS LEFT ELBOW STRUCK THE EDGE OF A BELT GUARD ON CONVEYOR 40117. MEDICAL TREATMENT WAS NOT REQUIRED UNTIL 10-2 3-03, AT WHICH TIME IT BECAME REPORTABLE. EE WASPLACED ON MODIFIED WORK.