As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
STL - DURING APPROACH WHEN LANDING GEAR WAS EXTENDED, RIGHT MAIN LANDING DOWN AND LOCKED GREEN LIGHT DID NOT ILLUMINATE. VISUALLY CHECKED RIGHT MAIN LANDING GEAR, IT WAS DOWN AND LOCKED. FOUND DEBRIS ON RIGHT MAIN LANDING GEAR INDICATION SENSOR. REMOVED DEBRIS FROM SENSOR AND LANDING GEAR INDICATION SYSTEM OPERATION CHECKED NORMAL.