As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
WHEN LANDING GEAR WAS EXTENDED, FLIGHT CREW REPORTED NO GREEN LIGHT (DOWN AND LOCKED INDICATION) ON LEFT MAIN LANDING GEAR. INFLIGHT EMERGENCY WAS DECLARED AND AIRCRAFT LANDED WITH NO PROBLEMS. AFTER LANDING MAINTENANCE VERIFIED GEAR WAS DOWN AND LOCKED. DEFECTIVE INTERNAL MICROSWITCH IN RETRACTION ACTUATOR.