What was found
(CAN) REPEAT SNAG OF YAW HARD OVER. AUTOPILOT WAS DISENGAGED, YAW DAMPER CENTERED, THEN YAW DAMPER DID ANOTHER HARD OVER, REPLACED RUDDER PCU, REPLACED YAW DAMPER COUPLER. PREVIOUS YAW PROBLEMS A/P ENGAGED , A/C YAWED TO RIGHT, A/P DISENGAGED THEN RE-ENGAGED. AIRCRAFT YAWED TO RIGHT AGAIN. A/P OFF, YAW DAMPER SELECTED OFF, NO ADVERSE YAW MOVEMENT. YAW DAMPER COUPLER REPLACED. IN CRUISE A/P YAWED TO RIGHT, A/P SWITCHED OFF, NO FURTHER PROBLEMS. YAW DAMPER REPLACED. INFO SNAG, IN CRUISE REDUCED POWER, A/C YAWED TO RIGHT AND THEN KICKED BACK. A/P AND YD WERE ENGAGED. NO FURTHER PROBLEMS REMAINDER OF FLIGHT. YAW DAMPED CHECK CARRIED OUT.