WHILE EMPLOYEE WAS HELPING FIX THE WINCH CANOPY THAT WAS DAMAGED IN THE TRANSIT, AFTER PULLING THE CANOPY UP THE LEGS THE METAL SLID ON METAL CAUSING THE CANOPY TO MOVE FASTER THAN EXPECTED, E MPLOYEE'S THUMB WAS CAUGHT BETWEEN THE WINCH CABLE ROLLER AND CANOPY. EMPLOYEE SOUGHT MEDICAL ATTENTION UNTIL 9-23-03.