Recently traded for a Blackstar HT5 head and am having an issue I’ve never experienced before: The clean channel’s volume won’t go down to no output (0). The dirty channel, no problem. Turn it to 0, no sound at all. Clean, it gets quiet and the other way, gets kinda loud, but won’t go to 0. And frankly, I don’t know if it’s going up as high as it can either. The pot feels good, no play or grind. It physically makes the whole sweep properly. If I tap it, I don’t get any static or cut out. The amp honestly looks very clean, no signs of abuse that I can tell. Anyone ever have this issue before? Or any clues as to what the issue may be or how to diagnose it?