As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
CAPTAIN CDI OSCILLATES ONE DOT LEFT AND RIGHT ON LOC/VOR FREQUENCY, CAPTAIN RMI PIVOTS 10 DEGREES LEFT AND RIGHT ON VOR/LOC FREQUENCY. BOTH OCCUR ALSO WHEN CAPTAIN ON AUX. REMOVED AND REPLACED GPS NMC AND NAV CONTROL HEAD OPS CHECK GOOD ON GROUND. TEST FLIGHT CDI OPERATES NORMAL ON CAPTAIN AND F/O'S SIDE IN NORMAL MODE. (M)