As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
GEAR DISAGREE AFTER PUTTING THE GEAR HANDLE IN THE DOWN POSITION ON APPROACH. BOTH MAINS WERE NOT DOWN AND LOCKED. NOSE GEAR INDICATED DOWN AND LOCKED. FOLLOWED QRH. PULLED MANUAL GEAR EXTENSION RECEIVED 3 GREEN. EMERGENCY DECLARED - TOWER HAD EQUIPMENT STANDING BY AS A PRECAUTION. FLT 5534. REMOVED AND REPLACED MAIN LANDING GEAR SELECTOR VALVE IAW AMM 32-32-10, OPS CHECKED GOOD.