What was found
WHILE AT CRUISE FLIGHT, AMBER FUEL IMBALANCE EICAS MSG WAS RECEIVED. FUEL WAS 2820 LT TANK 3100 CTR 3320 RT TANK. EMER & ABNORMAL CHECKLIST WAS ACCOMPLISHED & PROBLEM BECAME WORSE. IMBALANCE REACHED 700+ POUNDS & EMER WAS DECLARED & FLIGHT DIVERTED. AT NO TIME WERE WE ABLE TO MOVE FUEL INTO LT WING TANK. REMOVED UNSERVICEABLE LT WING OTBD FUEL XFER SOV PN 2970013-101, SN 1420. INSTALLED SERVICEABLE TESTED FUEL XFER SOV PN 2970013-101, SN 1389 IAW AMM 28-20-06. PERFORMED LEAK & OPERATIONS CHECKS WITH NO DEFECTS NOTED.