As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AFTER TAKEOFF WHEN LANDING GEAR LEVER PLACED IN UP POSITION ALL LIGHTS WENT OUT. WHEN HANDLE PLACED IN OFF POSITION, BOTH RED AND GREEN LIGHTS ILLUMINATED AND ACFT WAS SLOW TO CLIMB WITH NOTICEABLE YAW TO THE RT. WHEN HANDLE PLACED IN UP IAW QRH, LIGHTS WENT OUT AND YAW WENT AWAY. R & R MLG PRIORITY MODULAR VALVE IAW AMM.