EE WAS STARTING TO OPERATE THE LOCOMOTIVE. HE HAD REACHED OUT WHILE STANDING IN THE OPERATOR'S COMPARTMENT TO GET THE TROLLEY POLE. AS HE PUSHED DOWN ON THE POLE, HE FELT PAIN IN HIS LEFT SHOU LDER. THIS SHOULDER HAS BEEN HURT ON A PRVIOUS INJURY. NO OTHER FACTORS WERE INVOLVED. NO DAMAGE OR IMPAIRMENT TO THE MINING EQUIPMENT OR OPERATION.