Miata Steering Rack Clunk-Gear Retainer
 

I've narrowed down a clunk in my steering rack to the steering gear retainer on the passenger side of the rack. The part is #13 on the attached picture. It slides back and forth about a millimeter when I turn the wheel back and forth.

The spring clip on the end of the rack that holds the gear retainer in the rack is still there and seats properly.

Has anyone had this issue, or have any advice on how to fix it? I'm not overly worried because it doesn't seem to affect the steering at all, but if I could fix it without replacing the rack, I would like to.