@jdefran I use a simpler version of the posted Cleaning Guides.
Razor blades on the inside of the bowl and lid. If there are any heavy spots on the outside I'll hit them with a blade as well. Don't be afraid of it -go to town.
Then I follow up with SOS pads (soapy steel wool pads) on the inside and outside, and the razor on any stubborn spots.
SOS pads on the vents and legs too, followed by Mothers.
I actually enjoy cleaning kettles because they respond so well to the work put into them.