"Hhmmm. As I've said before, I'm reluctant to replace that power resistor
with anything higher rated. "

It is NOT higher rated. A 100 watt incandescent in that spot will limit the current even lower and there is less chance of blowing anything else.

I did not mean to suggest that you change your plan of troubleshooting, just that next time when it comes to a hot test, use the bulb. If something is still shorted you have a hell of alot more time to figure out what, rather than having overheat in seconds. When the light dims, you probably found the problem. the light goes down in resistance as all the filters charge and get almost to full voltage, once it does that it works without a net. Regular fuse and all that.

I consider a dim bulb tester a must for this type of work.