What was found
CREW DECLARED EMERGENCY, LEFT WIND FUEL CROSSFLOW RAN CONTINOUSLY AND IMBALANCE GREW TO 600LBS WITH LT WING LIGHT, UPON LEVEL OFF IMBALANCE BEGAN TO CORRECT AND RETURNED TO A BALANCED STATE. UNCOMMANDED YAW MOTION AT FL330, DESCENDED TO 270 AND YAW STILL PRESENT EVEN WITH AUTOPILOT OFF AND TRIMMED FOR STRAIGHT FLIGHT. COMPLIED WITH QRH AND UNCOMMANDED YAW STOPPED. NO EICAS MESSAGES NOTED DURING FLIGHT. REPLACED THE LINEAR ACTUATOR AND PERFORMED OPS CHECK OF ACUTATORS WERE GOOD, CABLE TENSION GOOD, FUEL CROSSFEED CHECKED GOOD, REPLACED THE RUDDER POSITION TRANSMITTER AND OPS CHECKED GOOD.