As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
SEA - GEAR INTRANSIT LIGHTS CAME ON, BUT GEAR DID NOT EXTEND AFTER SELECTING GEAR DOWN. GEAR HANDLE CYCLED UP AND RED LIGHTS WENT OUT. ALTERNATE GEAR EXTENSION PERFORMED AND GEAR EXTENDED. AIRCRAFT LANDED WITHOUT FURTHER PROBLEM. AIRCRAFT FERRIED TO PDX FOR REPAIR. LANDING GEAR SELECTOR VALVE REPLACED I/A/W MAINT. MANUAL. VALVE OPS CHECKED GOOD ON GEAR SWING. AIRCRAFT RETURNED TO SERVICE.