INJURED EMPLOYEE WAS LYING UNDER THE HAUL TRUCK ON HIS BACK CHANGING A HYDRAULIC HOSE THAT WAS DAMAGED. AS THE EMPLOYEE WAS USING A WRENCH TO LOOSEN THE HOSE HE FELT A PAIN IN HIS LEFT SHOULD ER. THE EMPLOYEE HAD AN MRI THAT REVEALED A FULLTHICKNESS TEAR OF HIS LEFT ROTATOR CUFF. EMPLOYEE HAD SURGERY ON 7-31-00 AND BEGAN LOSING TIME ON 8-1-00.