An old Zenith engineer once told me that Admiral needed the
color fidelity pot to compensate for the color temperature drift
caused by the 6LE8 demodulator tube.This tube is a high
level demodulator with built in matrixing.They were trying
to copy Zenith's scheme of high level demodulation to save money by using less tubes but
could not use the sheet beam demodulator tubes that Zenith
used.I guess Zenith had a patent on that circuit.Motorola
also used the 6LE8 but they decided to call the pot the
tint control.I think the proper way to adjust the color fidelity
is to turn the color intensity all the way down for a b&w picture.
Then adjust color fidelity for the best grey scale.You may also
want to install a fresh 6LE8 because this tube is pushed kinda
hard in these sets.
Swanson