"Peter T. Keillor III" wrote:

How do you true up one of the 6" plate mounted wheels? Just nudge it
around until it looks good, tighten up the screws and try it, or is
there a more systematic way?

No idea of the official way, but the way I centre stuff in a lathe is
.... and this should work for a grinding wheel.

Using the rest, find the part that is most out, then turn the wheel 180
degree and measure the difference, then go back and nudge for half the
distance. Repeat ad nauseum.