What Mod Is This? Dave Meniketti's 74 Super Lead

I'm wondering what mod this is? I drew an arrow pointing to it.
I see there is a Cross Line master volume connected to volume II. That's pretty obvious.

Is that purple jumper wire some sort of one wire mod? I can't quite see where the purple wire is soldered.

Anyone know or have any ideas as to what it might be?

Thanks!

 

Strange. A wild guess but it seems as if the pink wires running from the PI coupling caps to the volume II is a PPIMV

Surely it's a modded amp

 

Thats the 3 wire mod.

 

That may be a repair not a mod, can't see where it goes

 

time to get out your meter set to continuity and figure out where it goes

 

yeah it’s hard to tell.

 

looks like it’s shorting the 470k mixer resistor to ground?

 

As matttornado suggest, i think it's simply shorting the unused normal channel mixer side to ground. They could just have grounded the other end of the brown wire, but without a better pic?....