I have ended up with a similar set up...one day, I am going to try the pulley system, but right now I'm using that steel core fishing line directly from the rudder horn to one side of the water rudder, another line connecting the two water rudders, and the third line from that water rudder, back up to the air rudder.....sort of a triangle pull-pull.... it doesn't stay centered very long, and tweeks are required....maybe I will try Jim's spring trick...