I have some old 28mm cavalry that I am trying to refurbish. They have a white film in some of the recesses. I have tried to clean them with paint thinner, water, and (forgive me) saliva without success. Does anyone have any suggestions? Ideally, I would like to clean the entire mini without damaging the paint job. As last resort I might try a wash, but I really didn't want to make the figures darker.