Firmware updates do not help with this. You should do a factory reset (remember to save all your settings, if you want to keep them) and if that does not solve the problem, it is obvious that the mixer needs to be sent in for repair. Many times it's the faders that need to be replaced. As far as I remember channels 1-8 should be on one fader board, channels 9-16 on a second and Subs and Mains on a third. If the faders are the problem, get them ALL replaced! Talk to your service center BEFORE you send the board in.
