EE WAS IN THE PROCESS OF INSTALLING A TROUGHING ROLLER ASSEMBLY. WHILE HE WAS HOLDING A MOUNTING BOLT WITH A WRENCH IN HIS RIGHT HAND AND TIGHTENING THE BOLT WITH A 1/2"" DRIVE SHORT HANDLED SO CKET WRENCH WITH HIS LEFT HAND, HE FELT A PAIN IN HIS LEFT SHOULDER. HE WAS EVALUATED BY A PHYSICIAN AND PHYSICAL THERAPY WAS STARTED ON 8-10-00.