If there are any dark spots on the traces under the green masking the masking is removed and the contamination is removed. I have seen a lot of repairs done with these spots being left and over time the spots grow and eventually eat through the traces.
the dark areas that i have exposed in the photos below are obviously bad but every dark area and spot you see in the photos will be corroded and if left untreated will become just as bad the area i have exposed
