I have a Regency Insert. Up until last week I had a pot on top of the stove to hold water and humidify the room a bit. The pot has Riveted handles. I am on well with hard water so my softening system puts a lot of sodium into the water. Consequently, I get a lot of sediment etc in the pot. Last week I noticed the pot was leaking from one of the handles. Apparently the salt corroded the rivet. Now I have a white water stain on top of my insert. I have not had a chance to run the stove cold yet, so the best I could do was to try to wash it on a morning restart. This has proved fruitless. Any idea how I can remove the water stain without compromising the paint on the top of the insert?