Okay, swapped out the tubes - they had the wrong power tubes in there. Either for a certain effect or whatever, but now I have the right ones in. The old tubes look fine so I'll keep them for my Fender Champ build, at least the Preamp tubes. I was just going to ask on here what my next step is because the problem hasn't gone away. It's still crackling on the clean channel. I don't think I'm getting anything weird on the gain channel. Gonna chopstick it. Thanks for the info again fellas.