I removed the gray water tank and found two cracks in it.
Removed the Thetford valve and replaced the gaskets and plastic welded the tank. The belly pan was is such poor condition I was unwilling the reinstall it so I took it to my local sheet metal shop and had them make a new one using the old one as a pattern. I tested the welds by filling the tank with water installed the tank, valve, and belly pan, after checking for leaks.
I'm still not sure why or what caused my power issues.