As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ON DESCENT INTO LAX LEFT THROTTLE WOULD NOT RETARD USING AUTO THROTTLES. DISCONNECTED AUTO THROTTLES AND TURNED OFF AT ARM SWITCH. STILL UNRESPONSIVE. AT FL 190 THROTTLE BECAME RESPONSIVE. CONTINUED ARRIVAL APPROACH AND LANDING USING MANUAL THROTTLES. CRUISE WAS FL 380. REMOVED AND REPLACED LOWER POWER CONTROL BOX IAW AMM 76-11-10-4 UP TO ITEM H.