Learned that lesson the hard way too, now I always throw a load on it before I touch anything else. Meter the run with the strike firing, wiggle the splices while you watch the voltage, and nine times out of ten the problem shows itself. Corrosion in a crawlspace is the worst because it reads fine until something actually pulls amps through it. You did right by that lady, a 20 cent fix beats a sales pitch every time. Swapping panels just because they're old is lazy troubleshooting, and half these old systems will outlive the new junk anyway.

Man that would stick with me too. Five weeks of watching someone live like that every morning over eggs would mess with your head, especially when you never even got a name to follow up with. I spent three months in Oaxaca once next to a dude who did freelance design maybe ten hours a week and just... existed. Ate cheap, walked everywhere, never stressed. Part of me was jealous and part of me kept waiting for the whole thing to fall apart, and as far as I know it never did. The not knowing is the worst part, right? You just have to sit with the question forever.