As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AT FL 390 BEGAN TO EXPERIENCE DUTCH ROLLS WITH AUTO PILOT AND AUTO THROTTLES ENGAGED.DISCONNECTD AP BUT HAD TO HOLD THE YOKE TO THE RIGHT TO MAINTAIN CONTROL. DELCARED EMERGENCY AND DIVERTED TO ST. LOUIS. MAINTENANCE PERSONNEL REPLACED RIGHT CSEU POWER SUPPLY.