The annyoing thing about Kroil and PB Blaster is much the same as WD-40, the active ingredients are secret, listed under a % of proprietary agents. There is more than a bit of wild goose chase involved when going for one or the other, or just trying different stuff. There are brands that make different blends and let us know what the active ingredient is, like CRC. Applying the right stuff and let it go to work is probably the only way in cases like this, let it stand for a week or three, then reapply or altering with something else.