Guv'nor woes (buzzzzz)

[GibsonGM]

Built a Marshall Guv'nor, and it sounded great on the breadboard.  I changed the LED's to 1N914s for more distortion, changed the 100K gain pot to 250k, and used a modified BMP tone stack to avoid the 3 knob deal and still get a mild mid scoop.
Worked great on the board, a sick sounding lead pedal...

Now it's soldered, and I have a horrid buzzz (120 hz, maybe? It's really buzzy even with guitar volume off or unplugged).     Audio probe reveals the buzz starting on the return of the gain pot, so obviously something before there is making a buzz & being amplified.  Input is reasonably quiet, but there's a lot of amplification going on.... I've checked all connections, used a new TL072, no dice.
I'm wondering if I need to up the filter cap, or if the power section might be too close to the input?  It's only 3 perf-holes away.  Is there any way to tell without unsoldering the whole d@mn thing?
After building a couple dozen pedals, this has me mystified and feeling like a noob all over again!!   

[GibsonGM]

Anyone?  Why would I get 60Hz and its harmonics when using a battery?  Could be outside interference?   I measured the spectrum on a PC O-scope (Visual Analyzer, it's pretty good) and that's what I get. 

[DougH]

Did you put a filter cap on the Vr rail?

[GibsonGM]

10uF at the Vr tap...think I should try something like a .1uF after the 1M biasing resistor?

[DougH]

No, it's probably something simple- a loose ground, ground loop, etc. I'd look through the "what to do when it doesn't work" stickies.

[GibsonGM]

Probably a ground loop...been thru all of those.  This is the only pedal that's been stubborn, and I even perfed an Easy Vibe!    A 10n cap to gnd from the input kills the buzz, but also the highs.   I need this done for a gig on Sat.   Thanks for the lead to the Guv'nor, BTW, I really like it and will like it more when it's not buzzing  )