As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FLIGHT 5250 - DURING CRUISE FLIGHT ENCOUNTERED NOTICEABLE GENTLE OSCILLATION IN AFT CABIN, DEACTIVATED AUTO-PILOT AND YAW DAMPERS OSCILLATION PERSISTED. AIRCRAFT REQUIRED EXCESSIVE TRIM FOR COORDINATED FLIGHT. PERFORMED ISOLATION CHECKS OF PCU'S, NO FLUCTUATION NOTICED, ALSO PERFORMED VISUAL INSPECTION OF HORIZONTAL STABILIZER AND WINGS, NO DISCREPANCIES NOTED.