As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
SEA - FLT 574 - AIR TURN-BACK. CREW REPORTED ALL 3 GEAR RED LIGHTS ON AND GEAR WARNING HORN SOUNDED AFTER GEAR RETRACTED. CYCLED GEAR AND CONDITION REPEATED. REMOVED AND REPLACED THE LEFT THROTTLE SWITCH ASSEMBLY S319 AND OPERATED NORMALLY. (X)