INJURED WAS TAKING UP SLACK IN BELT BY USING A GRIP/HAND HOIST WHEN ANOTHER EE ATTEMPTED TO HELP BY ""BUMPING"" BELT FORWARD WITH DRIVE MOTOR WHICH CAUSED INJURED'S HAND TO SLIP OFF HANDLE ALLOW ING IT TO STRIKE LEFT UPPER LEG. REPORT LOST DUE TO HOLIDAYS - OFFICE WAS CLOSED.