As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
LANDING GEAR WILL NOT LOCK ON EXTENSION. MANUALLY PUMPED GEAR DOWN AND LOCKED WITH THREE GREEN LIGHTS. WE FOUND THE RH ENGINE HYDRAULIC FILTER RESERVOIR LEAKING FROM THE O-RING. REMOVED HYDRAULIC FILTERS VERIFIED NO CONTAMINANTS AND REPLACED O-RING. THE HYDRAULIC SYSTEM WAS SERVICED WITH 400 ML OF 5606. AFTER ENGINE RUNS, SERVICE HYDRAULIC SYSTEM ADDITIONAL 50ML 5606 AND NO LEAKS NOTED.