I just did a quick measurement on my 7D15, with the plug-in installed in a horizontal slot,
and being fed a 1 MHz 5 div p-p sine wave from a vertical amplifier. The 7D15 was set to
measure frequency, TRIGGER B selector set to TRIG SOURCE.
The 5 div signal from the vertical amplifier becomes a 840 mV p-p signal measured
at R117 with a 10X high-Z probe. It is symmetrical about 0V. Observing the signal
here will tell you the effect of the Q203/Q213/Q217 amplification stage, and you
should be able to see any contact resistance issues with cam switch contact
R117 is readily accessible with the right mainframe cover removed if you install
the time base in Horizontal slot A, and the 7D15 in the Horizontal slot B.
I hope this helps,