As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
SEA FLIGHT NR 21796, ON TAKEOFF OUT OF SEA, LOST ALL ABILITY TO USE AFCS EXCEPT FOR V/L AND AUX BUTTONS. NOTICED WHEN NAV SEL WAS PUSHED THE HSI SEL SWITCHED SIDES AUTOMATICALLY. MAINTENANCE REPLACED FGC IAW MTC 90340023. OPERATIONAL CHECK GOOD. AIRCRAFT RETURNED TO SERVICE.