Ogri

After some advice. Just stripped my 1986 calipers to refurb and the pistons are good at the top but at the base theres some moderate corrosion. Tried cleaning it off with a soft wire brush in a dremel and it feels smooth but wont clean off. As its the part below the seal and shouldnt pump any were near, will the pistons be ok or should they be replaced. Cheers Ogri