Today, the voltage remained steady at 4.98 on pin 23 while I turned the Depth knob. I grounded to to the chassis with an alligator clip to eliminate (or at least reduce!) the chance of error while I had the probe on the pin and turned the Depth knob. As before, the only change was that the Rate LED would start blinking at spots from 10:00 to 2:00 on the depth control.
The only other observation I can offer is that if the probe slipped between pins 27-28 or 28-1, the Bypass LED illuminated.
– Grady