Please see this thread,
page 2 with the pictures installing washers on the rudder and steering linkage. I did this today and my new Prostar is a very different tracking boat. Greatly improved and responsive. Thank you Chuck Dickey, you made my day.
Quoting Chuck's post, "I drive lots of different boats, brands and years and my new ProStar is the best IMHO. I know there are rudder adjustments that can make this boat feel like it's on rails. I had the opportunity to speak with Will Bush and he told me how to dial it in. These picture show a couple of washers I installed to take out any play in the linkage. Worked great, thanks Will."