EMPLOYEE WAS ATTEMPTING TO REMOVE FEEDBOX/SPLASH PAN TO 6'X16"" VIBRATING SCREEN WITH THE HELP OF TWO COME-ALONGS. THE SCREEN FEEDBOX SWUNG DOWN AND STRUCK HIS LEFT THIGH CAUSING A CONTUSION AF TER BEING UNBOLTED FROM SCREEN. EMPLOYEE WENT TO SEE COMPANY DOCTOR ON 8/27/03 AND WAS PLACED ON RESTRICTED DUTY.