I have a 2-1/4" Wico that I am currently restoring. The trackball was in relatively good shape. I washed it several times, soaked in soapy water ovrenight, soaked in bleach water overnight, and washed again. The ball is very white now, but there are still rust stains that didn't even budge from sitting on the rusty parts inside. Does anyone have any advice on how to get rid of these, or is it as good as it gets?