I bought this mixer new and it's been racked in my home studio and unused for the past 10 years or so. I have never had a problem with it. When I plugged it in to use it worked fine but I noticed some smoke coming from the sub mix near the main mix fader probably 2 or 3 and immediately turned it off and haven't turned back on. So I think you can bypass those, change if needed, or it was dust. I don't know so asking $100 obo