That's an excellent Job. Nail Polish remover is too weak, and your board does not need Vitamin E. But at a Beauty Store you can get a small bottle of Pure Acetone for under $4. Or you can get a gallon of the stuff at the hardware store for under $20 (I hear you get it for about $12).

Get a $1 tooth brush from the dollar store and a cheap bottle of 70% or higher alcohol. Scrub the corrosion spots with the toothbrush and acetone, rinsing the spot with a tin bit of acetone, and then a final rinse off with the alcohol.