I made one from foam like this one listed at avery tools, I made it the same dimensions as shown except longer. duck tape it to the rudder fly the plane if it to much cut some off, if not enough make it longer. when its just right, glass it over then glue it to the rudder.http://www.averytools.com/prodinfo.asp?number=9883
Or if you dont like that, make a bendy tab from aluminum and pop rivit it to the trailing edge of the rudder. That is how they do it on the columbia 400.
Strange...most -10's need right rudder input since the fin doesn't have any offset.
I set my tablesaw at 10ยบ and ripped a 1 1/2" wide piece of oak, 8" long and duct-taped it to the left side of the rudder and went flying. It was a little too much, so I cut off an inch...perfect.
It could simply be that the original poster's vertical stab is offset too much. Getting the correct offset in the stab while keeping it vertical can be tricky.
I would recommend removing your wheel pants and gear leg fairings and go flying. If the ball is centered, your fairings are not aligned properly. It would take quite a bit of misalignment in the fairings to cause an issue, but it is possible and I personally have seen it happen on a friend's RV.