As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT WAS GROUNDED. AFT FLIGHT ATTENDANTS REPORTED DIRTY SOCK SMELL. REMOVED AND REPLACED AUXILIARY POWER UNIT TURBINE CAVITY VENT SEALS (AALA201707269028) PER AMM 49-91-53. LEAK AND OPERATIONAL CHECK GOOD. ODOR REPEATED ON 7/23/17 RESULTING IN APU CHANGE SEE AALA201707269016