As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT NOT GROUNDED: UNCOMMANDED AUTOPILOT DISCONNECTS OCCURRED MULTIPLE TIMES AT FL390 WITH EITHER SYSTEM A OR B ENGAGED. NO OTHER AIRCRAFT DISCREPENCIES NOTED AT TIME OF DISCONNECTS. PERFORMED BITE ON DFCS AND FOUND MULTIPLE FAULTS ON BOTH A AND B CHANNELS. REMOVED AND REPLACED MODE CONT. PANEL IAW M/M 22-11-34.