Gallien Krueger 1001rb schematic FOR PREAMP

[rockman627]

I had to change the volume and master volume pots. The old ones were difficult to remove and I may have nicked the pcb doing so. I can get sound out of the fx send jack, but nothing when I plug into the fx return. I would like to verify signal passes thru the master volume to the fx return. But although I can find plenty of schematics for the power amp, I can't find anything for the preamp.
Can anyone point me in the right direction?