Steve wrote:
Neither of these radios could be called high performance,
and in fact represent the bottom of the barrel. Could new
tubes help? Possibly, but don't expect much. The best thing
to do is test the tubes on a reliable tester, and replace any
that are weak.

Steve

Recapping is a first step. You might achieve an increase in performance
by checking all the resistors to see if any are more than 10% out of
range (usually they age higher in value).
This will let the tubes operate closer to their intended ranges. Also a
total alignment is recommended after recapping. Check out the S38 Guys
website for other hints on that radio.
Lastly, make sure that you are using a good antenna. Mike KF6KXG