I need to clean a smooth top electrical stove, I dont have acleaning lady and she used to do it , (not any more)... Hot cocoa spilled and burned been cleaning it since yesterday, with the commercial stuff it's allmost o.k. but the white circles are grey in some spots I'm affraid I erased them or could it be that it's still dirty?? if i touch them I feel the line but its gray or black. Any suggestions. erika