First off he is using S-video so the chroma & video are separate already.
SO tuner, IF, video amps, comb filter, delay line are OUT of the pix.
IMHO the problem is a failure NOT inherent in the set. Its just too damn
obvious. This is a CTC166 not a cheap red China product. It was as good
as any at the time. Problems were few. I just remember some bad tuners,
bridge rects & the 9 V sense. The set uses a lot of SMD's for resistors &
transistors so that complicates things a bit. The order things get done
depending on the price of the IC is......
Change all chroma & VCC electrolytics.
Measure all IC voltages & scope all VCC's & GND's.
Pull IC & check all SMD's before replacing IC.
Replace IC
Call RCA TA ( they were very good ). If still no joy send to RCA service.
If you just decide to get an other RCA of this vintage add the CTC169 to your list. Its the top of line at the time & IMHO the best RCA ever built. I loved
working on them cause they always came out so good.
73 Zeno
LFOD !