Sorry to take this thread off topic (LOL) but,....
I am still looking for the correct schematic and the parts list for 50-C-3 . The one I have must be for the earlier version as it shows C2 (A) 500uF and C2(B) 500uf but the caps I have installed in the preamp are C2 (A) 1000uF and C2(B) 500uf.