As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ODOR LIKE SMOKE REPORTED IN MID-CABIN BY FLIGHT ATTENDANTS DURING PUSH BACK. ODOR DISSAPATED BUT REOCURRED DURING TAXI OUT. RETURNED TO GATE. *S/D* UPSTREAM INLET CHECK VALVE DESTROYED CAUSING GASPER FAN TO INGEST PARTS. REPLACED GASPER FAN AND CHECK VALVE.