EMPLOYEE WAS CHANGING A RETURN IDLER ON #2 BELT WHILE STANDING ON AN INCLINED BANK UNDER THE CONVEYOR FRAME. HE HUNG HIS 2# HAMMER BY THE HEAD ON THE CONV. BELT. HIS FEET SLIPPED ON THE BANK A ND HE PROBABLY HIT HIS HEAD ON THE HAMMER HANDLE WHEN HE FELL. THE HAMMER HIT THE BACK OF HIS RIGHT HAND BRUISING IT.