[Boatanchors] SX-122 hum and noise

[Byron Tatum]

Hello-
    I am trying to root out two types of objectionale noise coming out of audio channel on mySX-122. The receiver has a  new filter cap, that I have ruled out, as there is no ripple on the B+. I recently installed shielded leads on the AC power run from rear panel to front panel on/off switch. It did not seem to help.
        1. A constant hum is present in the audio, it is not too terribly objectionable but quite a bit more than any of my other tube receivers.
        2. A lower pitched hum is added in when the BFO is turned on, and this hum is noticably louder. The hum does not change in any way as the BFO is tuned.
    I believe hum in the audio has been a common problem with these sets, does anyone have any advice or info?
                                                        Thanks, Byron.