Baja Daze is right. It isn't the SST in the prop, it is the remnants of the brillo pad. Get rid of that first.
Also, stainless is really stain-less, not stain-proof steel. It will oxidize under the right circumstances. I used to know what those were, but I forgot. (I have a degree in Metallurgy - but don't actively engineer anything, still have the books though)