Unfortunately there is residue with Krud Kutter; enough to even form electrical paths. I used it cleaning some picture tubes (all sides not just the front) for my video games and didn't fully rinse it off and when reattaching the anode wire and powering up I got some significant arcing from under the cap to the aquadag coating. Rinsed it off with water and alcohol and it was good from there.

KK eats latex paint easily, including 35 year old hard dried latex. It will easily eat off white coatings on the back of marquees/backglasses/bezels. It works wonders for removing nicotine/soot and other baked on layers; but at the cost of quickly lifting any non-enameled coating.

Since it's water based, I'd never use it directly on a playfield; and take super extreme care using it on any silked plastic as it may lift one or all of the layer of paint.

KK has it's uses but keep away from anything with latex paint or wood unless you're extremely quick/careful.