Hi, I need to replace the output pot on my ux1, but I've been looking around it and it doesn't have any screw, I already pull out both plastic knobs on it thinking it had a nut below them, but as you know it doesn't, my warranty already expired so I don't want to take it to a service center, I can do it by myself anyways, it's not difficult at all, but at the moment I'm stuck on that, could you please tell me how is this unit opened? thanks in advance!