I was given some old Tryphon pen products and the instructions said that the scratch remover can be used to get rid of hard rubber oxydation. I tried it on a spot of hard rubber in a filligree overlay on a hard rubber pen. The problem? The only area that seems to go back to black is the center spot inside the filligree detail but not all the way to the edges. So, I have a spot of nice black surrounded by still oxydized hard leather. I tried Q-tips to get up to the edges but that didn't help. Suggestions?