what do you do to clean your LEE pots? a while back i made the mistake of melting wheel weights in my pot and now, no matter how much i flux, i still get black spots in my lead. i took it appart the pot and rubbed it down with steel whool as best as i could but the pot still seems pretty dirty. when i melt down the wheel weights, i flux it pretty good before they go into the muffin ingot mold. then when its in the Lee pot, i flux non stop but i still get black spots. any ideas?