cooked-on crust on porcelain stovetop
I am hoping someone has a suggestions how to remove extremely hard, cooked-on black crusty stuff from a porcelain-coated range top (below the burner grates). Ammonia won't touch it, plastic scrapers won't touch it, and I'm loathed to spray oven cleaner everywhere for fear of dulling the surface (it probably won't work anyway based on past experience).
This black stuff is rock hard and all the cleaning solutions I've tried merely soften the surface of it. We just bought the range (a Viking) used and I imagine the gunk has been happily baking there for years. The only way I've found to get it off is very carefully using the tip of a flat-head screwdriver but, as you can imagine, this is not the speediest method.
Any other hints?