If you simply spray the lead balls, with the white oxide in place, with WD40, the balls will turn black, but they will no longer oxidize, and the white oxide will become part of the ball again. The WD40 has dryers that evaporate the oil, leaving a film coating the metal( lead) which protect them from further corrosion.
I suffered a flooded basement 10 years ago, when snow on the roof worked its way down between the exterior walls of the apartment building where I lived. I didn't see the water, because it ran into a carpeted clothes closet, where I kept my range box on the carpet. Everything in the box corroded, and I spent considerable time removing mold, mildew, rust, and oxides from all the surfaces. The WD40 helped deal with several of the problems, better than all the cleaners I tried.