As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
UNIDENTIFIED SMELL REPORTED BY FLIGHT ATTENDANT IN AFT GALLEY. REPORTED SMELL AT THE GATE WITH ONLY EXTERNAL AIR HOOKED UP. FLIGHT ATTENDANTS THEN REPORTED THE SMELL GOT WORST AFTER ENGINE START. FOUND VACUUM GEN OVERHEATING AND CREATING ODOR. REPLACED VACUUM GENERATOR. (LP8441238, 8441239 - AIRCRAFT WAS GROUNDED)