As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FLIGHT ATTENDANT REPORTED SMOKE IN AFT CABIN AFTER TAKEOFF. RETURNED TO STL AND LANDED WITHOUT INCIDENT. REPLACED GASKETS ON LOOSE LEFT PACK PRESSURE REGULATING AND SHUTOFF VALVE 90 DEGREE ELBOW. REPLACED SOCKS AND ACCOMPLISHED CARDS 21-96-01 AND 21-92-12. SYSTEM GROUND CHECKED NORMAL OPERATION.