Hello David,
The shims are used to adjust the up and down play of the king pin assembly. Some up and down play is premissable (See BBB or Tech Data Booklet). Play from wear is usually movement in or out, at the top of the king pin (worn upper link pin, worn king pin or worn upper threaded bushing). Lower wear causing in or out movement at the bottom is usually caused by lower trunion, worn threaded trunion bolt or worn king pin. A little wear on all items can contribute to a pretty sloppy front end. Keep your suspension greased !
The bronze king pin bushings seldom wear, but are normally replaced whent he king pins are changed. these are pressed into place then reamed to correct size.
A quick grease job immediately before inspection could temporarily tighten up a marginal suspension.