I will respond to some of the posts above, without discussing the side topic of poorly manufactured capacitors etc.

1) the PS is rated at 35A, but I rarely draw more than 18A - and that is not a continuous draw.
2) I run the PS in a cool room, and also as a result of point 1 above the cooling fan has never come one (but has been tested to work). In other words the PS runs very cool
3) nothing has changed for 7 years until recently so this is definitely recent noise coming from the PS as I can switch to a deep cycle battery instantly and the RX noise disappears.

I have ordered the two 1000uF, 200V input caps and should replace them in about 3 days and will let you all know the results.