Boo, The fan should be fairly quiet, no rattles, and the mixer should not get hot--slight warm, but never hot. If it's getting hot, there's a good chance that the cooling fan is fried. The bearings on the fan motor are easily burned out, especially if you're playing in a relatively humid climate and smoke filled bars. The fans are not expensive and they're easily replaced. However, if you're one of those folks that needs help screwing in a light bulb, I suggest taking the amp/mixer to a service center. The fans are available in many compter stores and electronic shops for under $20.
Good Luck,
Gary
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PSR-S950, TC Helicon Harmony-M, Digitech VR, Samson Q7, Sennheiser E855, Custom Console, and lots of other silly stuff!
K+E=W (Knowledge Plus Experience = Wisdom.)