The bad cord was already soldered to the tip of the plug...mostly. There were a few frayed wires and one (yes ONE) strand appeared to be touching the sleeve, which would explain some noise. I noticed it when I jiggled the cord, then went looking in that connection. I found that and re-soldered it.
Not sure why it was louder in the B channel though.
The battery thing was a total surprise. I would have never thought about that, but I guess a small amount of noise was being amplified by the higher gain settings....which kinda makes sense as to why I didn't hear it in the cleaner patches. The dang thing sounds amazing now, screaming gains that get dead quiet with a quick palm mute. The difference is pretty noticeable. Thank GOD it wasn't in the preamp