John,
Your test equipment sure is classic. (Viva La BC-221). I use one
myself. Are you reading the freq directly from the vernier dial on the
221? Of course if you have the book and trust your 221, that should be
close enough. But a counter would be comforting.

I have an NC-270 and assuming that the filter circuitry is the same as
your 190.

Is your receiver working OK and you're just doing a fine alignment, or
are there other issues?

Where are you injecting the 230 kc signal?

Are the two threaded rods in the filter backed all the way out and
still won't hit 230 kc? I'm sure you're aligning the other 230 kc tuned
circuits along with the filter.

If there has been a change in the ferrite characteristics as Chuck
mentioned, possibly those two silver mica caps (3900 pf in the NC-270)
could be replaced with a slightly lower value. But I don't think that
type of change is likely here. An R-390 linear PTO would seem to be
much more critical.

John