Just thought I would let everyone know how I ended up doing the
alignment. I used the horizontal (sawtooth) output of the scope (Tek
545a) to drive the external FM input of the sweep generator (Hickok
288x). Set the scope for .1 sec/div (seemed to give about best looking
curve) and the generator for 5kc sweep, then monitored the output with
the scope vertical at volume control. The sweep was feeding the IF
section. Added a straight CW signal from an HP606a to create a "pip"
for calibration purposes, paralled to a 5245L counter.

So what did I see? With the SX-71 set for normal IF (AM signal) I
ended up with a nice bell curve about 4kc wide at the base. When I
switched the crystal filter in I got the sharp spike with adjustable
null as from the ARRL handbook pages Frank posted. Adjusting the slug
seemed basically to be aligning the IF with the crystal. When set for
what to me seemed best, I was able to create an adjustable null (using
phasing control) than ran from just below the cystal peak frequency to
maybe a kc or so below it. When the slug was way off the curve became
very distorted and the crystal would tend to oscillate (ring) much
more. The only unusual artifact I saw was a notch in the higher
frequency side of the peak, not shown in the books. Didn't seem to
hurt anything. It changed with higher sweep rates, so it must be
something due to my test setup.

After setting this slug I aligned the rest of the IF section to the
crystal peak, which was 459khz using just the AM signal from the 606
and monitoring the output on an HP400 rms meter. Everything seems to
be working well, but as this is my first communications receiver I
don't have much to compare it too. The crystal filter is useful on CW,
but also on some SSB signals when an interfering signal causes an
annoying audio signal as it beats with the BFO. I can now tune them
out.

Personally, I think sweep is the way to set this. Then you can really
see what you are doing. Short of that, I am not so sure just finding
the crystal peak and then aligning all the IF slugs to it wouldn't do
the job just fine. Thanks to everyone for their very helpful advice.

Dan