I did try ch2 with the same result
That's interesting. The input circuitry, including the circuitry and attenuator switches actuated by those V/Div knobs, are not shared between channels. Seeing the problem on both channels more or less rules out a lot of things.
Yeah I’m not totally sure what to make of it, based on the fact that I got a square wave from the bare wire on ch1 after turning the knob I figured the most logical next step would be to get an appropriate probe then see what happens on both of the channels. I didn’t try the bare wire on ch2 though, I just tried tuning the lecroy probe on it like I did on ch1. But now that the bare wire somehow went from the swept signal to the square wave I’m going to try both my lecroy and Agilent probe tomorrow just to see what happens.
Another theory I had was that it could have something to do with it having warmed up for longer, even though the other day I left it on for a couple hours before even trying the probe, and it was only on for about a half hour today before I tried the bare wire.
It could be that it was just chance that turning the knob wore through oxidation.