As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
APPROXIMATELY ONE HOUR INTO FLIGHT, AN ELECTRICAL OR METAL SMELL BECAME INCREASINGLY NOTICEABLE IN COCKPIT, ESPECIALLY ON F/O SIDE. THEN SEEMED TO COME AND GO. PERFORMED TSM TASK 24-00-00-810-823. FOUND F/O'S SEAT ASSY IS CAUSE OF SMELL. REPLACED F/O SEAT REF AMM 25-11-51.