I acquired a 4300 from my father inlaw years ago that he purchased new. It sounds great. The only issues seem to be some burned out bulbs, scratchy balance controls could use a new piece of vellum and a good cleaning. The dc offset hovers at less than 2mV on all the speaker outputs. I would like to do the work myself and would like some direction on parts sources and methods. One other odd thing the power switch when turned off cuts off the speakers but all the lights stay on and the meters operate? Anything helps thank you kind sirs!