What was found
DIVERSION TO ANC, ENROUTE CREW REPORTED EICAS MESSAGE FUEL IMBALANCE 1-4. CHECKLIST COMPLETED. NR 4 CONTINUED TO DECREASE, NR 3 REMAINED CONSTANT QUANTITY. SYSTEM CONTROL ADVISED AND AIRCRAFT DIVERTED TO ANC DUE TO FUEL LEAK FROM NR 4 MAIN TANK. MAINTENANCE ADVISED FLIGHT CREW TO SHUT DOWN NR 4 ENGINE. UPON ARRIVAL THE CAPTAIN ADVISED THAT HE WAS UNABLE TO MONITOR FUEL USE AND HAD TO SHUT DOWN NR 4 ENGINE. NO FUEL DUMPED. FOUND NR 4 TRANSFER VALVE PARTIALLY OPEN. REMOVED AND REPLACED TRANSFER VALVE ACTUATOR IAW MM. CMC GROUND OPS CHECKED OK. VISUALLY VERIFIED VALVE OPERATION OK.