I have a collection of old Chartpak "rub on" letters and numbers of various sizes. Unfortunately, they are so old (20 years or more) they won't rub off anymore. A few of them still work with extreme pressure, but most are permently attached to the sheet. I tried using a little heat from a soldering iron without success.
Any idea how to get the old letters to transfer to a painted surface, or should I just throw them in the trash?
-Bill