MEDICAL TREATMENT BEGAN 5-9-03 WITH RESTRICTED DUTY ON 5-12-03, FROM A MINOR FALL OFF THE BOTTOM STEP OF A 988 LOADER. THE OPERATOR WAS FINISHING REFUELING AT THE NORTH FUELING STATION, WHEN H E SLIPPED AND FELL DOWN ONTO HIS LEFT SIDE. HE GOT UP, SHOOK IT OFF, AND KEPT WORKING CONTINUOUSLY UNTIL 5-9-03, WHEN PAIN IN HIS LEFT SHOULDER REQUIRED MEDICAL ATTENTION.