As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
SEA - AFTER TAKEOFF MAIN LANDING GEAR WOULD NOT RETRACT. AIRCRAFT RETURNED TO THE FIELD WITHOUT INCIDENT. AIRCRAFT WAS FERRIED FROM SEA-PDX, WHERE THE COCKPIT SELECTOR PANEL AND SELECTOR VALVE WERE REPLACED. OPERATIONAL CHECKS GOOD. AIRCRAFT RETURNED TO SERVICE.