[ccomer1955]

Interesting results: with no leads in place, I'm getting a flat line for the most part. If I turn the v gain pot, it momentarily shows a spiked sine wave, then flattens. I get similar results with the 10x probe in place. Jiggling or turning the v gain pot gives me a spiked sine wave that settles down to a flat line with the probe plugged in or without. With it plugged in, I of course have the probe connected to no electrical source at the probe end.

So...really dirty pots?