As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ON DEPARTURE, NUMBER 1 AND 2 COMPASSES DIFFERED BY AT LEAST 45 DEGRESS. MAG COMPASS DIFFERED BY AT LEAST 40 DEGREES FROM KNOWN HEADING. MADE UNSCHEDULED LANDING AT JFK. REPLACED THE NUMBER 1 AHRS COMPUTER (P/N 460800-03-06M0D4), AND THE MAGNETIC COMPASS (P/N C4E). ALSO SWUNG THE MAG COMPASS. CHECK-C 10-14-99 MCI.