[Texasrocker]

You can feel free to: "cut loose" those old coils of wire wrapped around all those vintage wax caps! In some cases, those wraps add as a "resistance",(one end to chassis gnd),.. but that small amt resistance isnt anything to worry bout either. If your chassis has the old "crusty" rubber coated wiring now deteriorated, look closely for direct-shorts among the mess of orig point-to-point connections. Better yet, replace all those old wires 1 by 1,( point-to-point) carefully, and you may find any residual "hums" gone after doing so. Old "leaky wires" can cause probs sometimes indeed! Make sure your AC plug on your test bench is isolated from modern AC type noise generated from overhead florescent lighting fixtures, TVs, computers, etc.
Vintage tube type radios pick-up inteference from many modern day devices/ home appliances that cause "hum" probs. Just tryin to help!!