Marshall JCM600 drive channel noise incorrect component on circuit board?

[tonefiend]

Your problem is noise. I suspect when your resistors "tested out fine" that means the resistance was measured? Your ohm meter will not detect noisy parts. I vote R120.

Gentleman! Mission accomplished!

I replaced R120 and R121 with 1/2 watt metal film resistors, plate load resistors for v101b, v102a respectively, quiet as a mouse,
this amp is now in excellent working order and ready to gig...

thanks to all who helped me debug... all input was extremely helpful... ok , off to the gig!