OS-2 mods causing oscillation?

[comfortably_numb]

So I modded my OS-2 quite a while back to these specs:

c18 from 0.47uF to 1uF
c23 from 4.7uf to 22uF
D7, D8, D9, and D3 to red LEDs

I had been using it as a low drive booster (thus the LEDs) but recently decided to crank it up for some beefy distortion tones.

That's when I heard it...  A beating oscillation, sort of like a heartbeat.  Very strange.  The speed of the oscillation changes with as I move the Color control.  Fast toward the overdrive side, then nothing at the distortion side.  The level of this also changes with amount of drive. 

I've change the LEDs, ensured that everything was properly oriented.  Right now I have the original silicon diodes in D8 and D9, a 1n4001 in D7 and a 1n4148 in D3.  I was just switching things out to see if there was any difference.  I also tried a 47uF cap in c23, which only lowered the speed and pitch of oscillation.

Any ideas?  I've done a good bit of soldering on this board, so I'm afraid to do much more experimenting, and it's possible that the board is fried already...possibly causing the oscillation somehow? 

I've checked very carefully for solder bridges, and even run my knife through anything suspicious. 

Help!?!

Thanks,
CJD

[comfortably_numb]

::bump::

[WGTP]

I don't see anything that would cause oscillation in your mods.  If it stops on the distortion side, it is probably coming from the overdrive side?  I guess you could go back to stock and change the parts one at a time and see if you can figure out which one is causing it.