EMPLOYEE WAS REELING IN FUEL HOSE ON #65 FUEL TRUCK AT THE HOPPER WHEN THE BUTTON ON FUEL REEL STUCK AND JERKED EMPLOYEE'S LEFT ARM UP OVER REEL, INJURING TENDON ON ROTATOR CUFF OF LEFT SHOULD ER. NOT REPORTABLE UNTIL 1/15/04. FIRST DAY AWAY FROM WORK.