Hallicrafters Crystal Filter/Phasing Alignment... HELP!

I am aligning an SX-71 and just can't seem to understand the procedure
related to the crystal filter/phasing section located in the 3rd IF
circuit. The manuals talk about turning the output slug on the 3rd If
transformer (which feeds the filter) while "rocking" the signal
generator around 455khz with the BFO set to generate a 1000hz beat off
the 455khz signal (before rocking). You are supposed to look for a
notch in between two peaks (one large and one smaller) visible in the
audio output level. Well this is just too many variables for me. By
rocking the generator the beat frequency (which is the audio output)
ramps down through zero hz (and also volts) then back up on the other
side. That alone creates a notch in the output that has nothing to do
with the filter or IF slug. The filter, or my wiring hookup, causes a
few minor humps in output on the way to zero and back up the other
side. The slug seems to affect output levels in general, and doesn't
have an easy to discern impact. You are supposed to set the slug so
that it (the IF tuning I guess) falls into the notch... what notch???
There is a zero beat notch 1000hz down from 455khz... is it that
notch? Anyhow left to my own, I would tend to tune the slug to provide
a max peak on the crystal frequency, which is supposed to be 455, but
is 456.7. You are later to tune all the IF sections to the actual
crystal peak, which I have done. Anyway, I am clearly over my head.
Plus, this particular slug is stiff and the screwdriver slot broke one
side off, so I am using plyers to turn it. Not pleasant.

This is my first communications receiver so have some mercy. I did
learn how to twiddle the BFO to listen to SSB ham transmissions... fun
and the first time I have ever listened in to these folks. Also, with
the crystal phasing, the BFO, and some obscure signals out there you
can create some of the best 50s science fiction sounds I have ever
heard. Great fun!

Dan