SCA.6
If it doesn't have FM demodulation available at this frequency, then
can still use a trick called "slope detection".  Tune it above 67 KHz so
that the 67 KHz carrier falls on the lower slope of the IF selectivity
curve.  I.e. the signal has fallen off about halfway from its peak value
on the meter.  Select AM demodulation, and then tune for the best sound.
You should get acceptable recovery of the audio.  If there is a
bandwidth switch, experiment with it.  Probably the widest bandwidth
available will work best.

If you don't have a suitable VLF receiver covering 67 KHz, the simple
trick with the Phase-Locked Loop device will work just fine.  After
the monaural FM receiver has done most of the work of picking up the
weak signal at VHF (88 to 108 MHz) and amplifying it and FM demodulating
it so you have the baseband composite signal available to fool around
with.  What is going on here is that the PLL locks to the 67 KHz signal
but since that is being FM modulated, it has to work a bit to stay
locked.  The Voltage-Controlled Oscillator has to be pushed above or
below 67 KHz, its natural frequency, by applying a control voltage to
the VCO input.  All of this is done "automatically" by the design of
phase-locking circuitry, but YOU can benefit by all this work it is
doing: the control voltage is precisely a measurement of the
instantaneous modulation value, M, that YOU want to hear!  So you pick
it off, amplify it, and listen to MUZAK (yuk) to your heart's content.
CONTINUED IN SCA.7