Here's a trick we use on the round track racers sometimes. Look at the splines on the steering gear end of the Pitman arm, and you'll probably find at least one wide spline, with a corresponding area on the sector shaft of the steering gear. With a little careful work with a 3-cornered file, you can create a spline pattern on the Pitman arm that can be adjusted one spline at a time to help center the steering. Just split the wide spline into two regular-width ones. The tightness of the Pitman arm nut and the tapered shaft will keep things tight, even without the wide spline.
Jerry
