When you drop the rudder you will see two shiny (hopefully) stainless areas on the rudder post. One at the top and one at the bottom. Inside the rudder tube are 2 bronze bearings (bushings really) one at the top and bootom that coorespond to the shiny areas on the rudder post. I wrapped the shim stock around the rudder post at the lower bearing area. When I measured my rudder the upper bearing was not out of spec very much. If your upper bearing is out of spec by a lot say 3/16"-1/4" you will want to address that. I am not sure how easily it would be to get shim stock into that upper bearing but I suppose it could be done. Another option is to try and replace the bronze bushings inside the rudder tube but that would require some surgery and is not a job for the weekend warrior. Hopefully you will find what I found and it will be your lower bearing that is out. You need to drop the rudder and see what you got.