As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FLT 635 - MCI - AIR RETURN - EMERGENCY DECLARED, LANDING UNEVENTFUL. EXPERIENCED FUEL IMBALANCE AFTER DEPARTURE, RETURNED MCI. FOUND DEFUEL VALVE IN OPEN POSITION AND NR 1 TANK VALVE OPEN. DEFUELED AIRCRAFT AND ACCOMPLISHED KNOWN QUANTITY FUELING. CLOSED ALL VALVES. ACCOMPLISHED PRECAUTIONARY OVERWEIGHT LANDING CHECK PER GMM 7-4. (M)