As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(LOG 6896200) AFTER TURNING ON THE PACKS W/APU AIR AND NO GROUND AIR, THE FLIGHT ATTENDANTS IN THE AFT CABIN REPORTED A BURNING ELECTRICAL SMELL. FOUND APU OIL LEAK AT GEARBOX. REMOVED AND REPLACED APU STARTER GENERATOR SEAL PLATE REF B737 AMM 49-41. NO LEAKS NOTED. ALSO REMOVED AND REPLACED APU BLEED VALVE REF B737 AMM 49-52. REF LOG PAGE 6896203.