I have only ever used a simple soft erarser to clean the pins. Simply push the pins into the eraser a couple times . You can see the black it leaves behind and inserting them back in snug sockets will finish a clean contact. Pencils with eraser tips work well on the smaller pins . No need for chemicals or especially risking sanding off, or through plating either. Seams more like seeking a problem or creating one than needing a solution.