EE AND 2 CO-WORKERS WERE RAISING THE SLOPE TRACK IN ORDER TO MAKE IT HIGHER THAN THE WATER LEVEL. A 10 TON MECHANICAL JACK WAS BEING USED TO RAISE TRACK. EE HAD PLACED ON HALF HEADER UNDER TRA CK AND WAS IN THE PROCESS OF PLACING ANOTHER HALF HEADER WHEN THE JACK KICKED OUT CAUSING THE TRACK TO FALL. EE'S RIGHT THUMB WAS CAUGHT BETWEEN TRACK & HEADER. SUSTAINED AVULSION TO THUMB.