I bought a used Live a while back off Reverb and well, my input is now acting wonkie and the level it was producing a few days ago is barely audible now. When I turn the input knob in front, it crackles and spikes in output..low and high but it is still very low as opposed to what it was. I always kept my knob at the noon position and never had any problems with output until now. Anyone know where these machines can be looked at? I have no warranty.