[mikethedruid]

First, looking at the schematic, the resistor that goes between the center tap and chassis ground is 395 ohms, so that is what I would expect to see between center tap and chassis. that 395 ohm resistor appears to set the bias voltage for the grid of the #42 Audio output amplifier. The capacitor across it is to remove ripple from this bias voltage. Bigger capacity would work even better. I notice two capacitors marked number 10, both are .09mfd decoupling caps. If either of those are bad or miss wired, or cold soldered, you could have hum from them. I would replace them with .1mfd 600V poly caps, which you may already have done. Check and check your wiring again.