When light bulbs aren't really bad.

[Dr.Zoom]

So before swapping over to led interior lights I noticed a bunch of my interior lights were out, but when I pulled them, they weren't noticeably burned out looking. I wondered if maybe they weren't getting good contact, did a little testing and every one that wasn't burned out looking actually worked, and were just suffering from oxidation. So if you're tackling your lighting, remember they may not all actually be burned out, they might just need some cleaning. Cleaning the socket is a good idea anyway to get rid of 20-ish years of oxidation. I use Caig DeOxit, but there are other similar cleaners.

Just wanted to shed a little light on it in case y'all were in the dark too.