I have found a contact burnishing tool that works very well with
gold plated contacts. It is made by a company called "GC" and
is available at most electronic supply stores, except probably Radio
Shack. It comes in a little red holder and has a black handle.
It is far better than a point file or sandpaper and does a better job
than business cards. It is small enough to fit any switch contact
you may encounter and is specifically made for BURNISHING Gold
Contacts!! You can still use a point file for Flipper Contacts.