[HAM] excessive hum?

[Read Smith]

Hi Micheal, It sounds like your hum problem could be circuit based  
rather than tonewheel. THe AC circuits are
very dodgy on my gig. I have a Furman line conditioner which has  
reduced my AC hum to almost nil but this
new thing is there always there. Is there a way to test individual  
tonewheels? If I could be sure it is a tonewheel problem,
what would I do then?

Thanks