I gather this is the two or three turns of white wire pointed to by the red arrow in the photo at
http://antiqueradio.org/art/temp/RCA630TS17.jpg ?
I tried to attach the same photo to this message, but haven't done that trick before, so my apologies if it is hosed somehow.
Is the type of wire critical?
It looks like a fair amount of work to pull things apart to replace that wire. I think I will bring up the TV one last time in the dark, in hopes of (quickly) spotting the arcing source.
Meanwhile, I need to do more detective work to find the no-signal problem, which did not improve as hoped with the substitution of 3 new 6J6 tubes in the RF section. One of the coupling caps in that section is mica, so perhaps that's the culprit. The others are ceramic, which I am assuming (ha-ha) is very reliable.