When I did my 4 & 5N, I used Sams, RCA service publications, and also noted every step of the way just what each circuit looked like as wired, and had no problems at all other than what one would expect in a restoration. Low hours set, the 4, with all factory mods. One thing I did do in the 4 was put the chroma amp circuit back to original. I believe it was wired to bypass the automatic color control circuit to allow more gain. I like it the way the engineers designed it, but to each his own.
Kevin