As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
LANDING GEAR DID NOT EXTEND WHEN SELECTED. PILOT FLEW BY THE TOWER TO VERIFY THAT THE GEAR DID NOT EXTEND. AFTER DEPARTING THE PATTERN TO MANUALLY EXTEND THE GEAR, SUDDENLY THE GEAR OPERATED AND EXTENDED NORMALLY. MAINTENANCE DETERMINED THAT THE ELECTRIC SWITCH ON THE HYDRAULIC SERVICE VALVE WAS INTERMITTENT. THE SWITCH WAS REPLACED TO RESOLVE THE PROBLEM.