If you must use nyrod (not my choice, but one way to do it), then you have to secure the sheath to the structure of the plane at its end. I'm not seeing that here. So when you push the rudder one way you pull the sheath straight, and when you push the rudder the other way the sheath deflects, and there is enough internal friction to prevent accurate centering. Nyrod should be run as straight as possible. Excessive bends only add play and friction.

Also, previous comment is absolutely correct thet the nose gear arm should be at 90-degrees to the nyrod at neutral position.