As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING CRUISE, AT AUTOTHROTTLE MODE, THROTTLE CONTROL LEVER CONTINUED SHIFTING AND LT ENG EPR MAINTAINED 1.68. ALTERD TO MANUAL MODE AND FOUND LT ENG WAS NOT IN COMMAND BUT EPR 1.68 STILL. PILOT DECIDED AIR TURNBACK, AND SHUTDOWN THE ENG FOR LANDING APPROACH. INITIAL INSPECTION REVEALED FUEL PUMP CONTROL SHAFT WORN AT THE END WHICH COUPLED TO FCU.