[DonRotolo]

20Amp breaker, no wire is permitted to be less than 12 gauge, anywhere. Period.

Today, a dishwasher needs it's own dedicated circuit, as does the bathroom, but we're not trying to bring the house up to code. (which isn't a bad idea though)

A charred wire and rusted GFCI is your house's warning to you that there is something horribly wrong here, and it's giving you a chance to get it repaired correctly. Usually, you get only one chance.

Don't be foolish. If it was just a simple repair, or rewire something, I'd say go for it. Here we have symptoms that are downright scary and are never supposed to be seen - you need a pro to diagnose exactly what is going on so it doesn't burn down the house.

Don