[RFI] Mystery Noise (Aren't they all)

[Wes Stewart]

I have been plagued for months with raucous noise, primarily on 160-meters. Our power co-op has a tech who maintains their com gear and fills in as their RFI guy.  I gave him a plug at a meeting with the CEO and suggested that he needed better equipment.  So he has the latest Radar Engineers 243, ultrasonic dish, etc. But he's struggled to find this particular noise and I finally got him into my shack and connected to my antenna, which pegged his meter and gave him a signature.
The problem with this organization is if he finds a suspect, he has to request a line crew which usually shows up when he's not around.  That was the case here; he identified a pole, they came out later and said they didn't find anything.  This was all unbeknownst to me and a few days later I happily reported the noise was gone.  He said, "Huh, that's funny, they said they didn't fix anything." Of course, it came back.
It has a strong 120 Hz component, but overlayed on that is a lower frequency modulation that is frequency sensitive.  In other words, if I tune for example to 1830 kHz I might hear the low frequency noise (Which I have dubbed rotating machinery) and then tune just +/- 10 kHz the low frequency stuff goes away and I'm left with the background stuff.
In conversation with the tech a few days ago I offered to battery power my TS-890 and turn off the whole house breaker.  When I did the noise went from S9+10 dB down to about S4, but it was still there!   I re-energized the house but opened the breaker to the shack and the noise was the same as with the whole house turned off.
I have limited test equipment these days.  In addition to the shack transceiver I have a Sony ICF-SW7600GR, which with just a loopstick antenna, has proved to be nearly worthless, and a TinySA Ultra, that I haven't tried.
This place has a smart meter which radiates prodigious garbage within a couple feet or so on the Sony RX on several bands, but falls off rather quickly with distance.  The RFI guy has suggested that I get a meter maid out here to pull the meter while I run further tests.
Any other suggestions?