"Forgive me for questioning you, but something does not seem right.
Have you
checked the good S-20R to make sure that its oscillator is 455 kHz
above the
received frequency and not below? "

"Try this. Take your good S-20R and set if for say 10 MHz (wwv is
good).
Then, listen to the oscillator. Assume that is 10.455 MHz. Now, take
your
bad S-20R and set the dial to 10 MHz. Then, set your Icom to 10.455
and
adjust the capacitor until you hear the oscillator on your Icom. It
should
be working."

Did that. I wanted to verify that the oscillator operated above the
received frequency on band 3. (It does, same as on bands 1 and 2. It
operates at 455 kHz below received frequency on band 4).

In fact, I can align to the image and get it to line up at 7 MHz. Of
course, when I do that, the mixer and RF stages no longer track very
well, and it would be really annoying to have to turn the receiver on
its side and readjust those trimmers as you travel down the band. If I
align the correct way, the mixer and RF stages track (sorta)...better
than if I align on the image, but still not quite right (would make
sense if the oscillator is not tracking right....mixer and RF are
probably tracking fine....just not keeping in step with the
oscillator).

BTW...no need for forgiveness....without questioning it'd be danged
hard to figure out what's going on here....which is why I'm here to
begin with.