Hi man,
There's indeed a few ways people seems to do it.
But, the simplest would, as the name suggest, is just 1 wire.
And this is basically separating the 470K resistors, and tying one of em to the 68K resistors.
It's best to do it with a switch I think, to get back the stock plexi circuit.
And perhaps, to have a bright switch. My plexi doesnt have bright cap even on the bright pot. With the switch, that can be selected.
The hard part is, it can go a bit unstable when set very high. A lot of playing with the lead dress.
But you dont have to set it at 10 all the time. Balance the 2 vol pots to get the sound you want I guess.
I will make a layout soon. I'd footswitch the thing
(normal switch can also be used of course)
Thanks!
Nik