thats weird about the RF gain.
most of us leave it all the way up all the time.
only turning it down when someone pegs the needle on your meter.
does the hum get worse with the RF gain all the way up, and better with the RF gain most of the way down or is it the same no matter where you set the RF gain?
you might do well to get yourself a CB walkie talkie.
get one that has all 40 channels.
then, you can walk around the neighborhood and point the antenna of the walkie talkie at different things and see if the noise gets better or worse.
tune it to the channels you really get the interference (hum), and point the antenna at the power transformer.
point it at your neighbors house.
do the same with the star wars type noise.
just walk around the neighborhood waving that antenna around like a lunatic. LOL
if you really want to pinpoint the noise source, start lowering the antenna, and finding the noise again, until you have found the source.
i think a CB walkie talkie would be a VERY beneficial thing to have in your particular situation.
(also nice to hear how your radio sounds on the air!)
you can find these walkie talkies everywhere. check ebay and your local craigslist.
many people bought them and never use them.
shouldnt be too expensive.
take it easy,
LC