First, you can't take all the slop out of a NACRA or Prindle rudder and still tack easily. The rudders need to turn at different angles (see ackerman angle) during tacking and the slop provides a portion of that.

The basic idea for the bolt systems is not that they stay centered but that they return to center under normal conditions.

Try loosening the springs a little, you may have them so tight they are binding. (On the old Hobies, if you did that the bolt bent)

The bolt hole has to be bigger than the bolt, normally 5 to 10 thousands biggeer If the hole is more than ~0.0625 bigger than the bolt you might consider drilling the holes out and installing plastic bushing.

The slop in old Prindle and NACRA rudders used to bother me until I took it all out.

If you find you just can't stand slop in the rudders buy a Marstrom, they have different problems.