During the knife edge, the servo arm slipped on the spline. When I went to neutral, the rudder was now offset giving me that yaw and making the jet difficult to turn and keep level.

My F-4 is setup the same way! If I sell it, the new owner must switch to aluminum arms. If I keep it it will not fly with anything less than aluminum.

Wow, I have used these arms for years in all my jets...hundreds of flights between them. Never an issue. Blows my mind.