Just an update for other fellow who might be looking for a safe method to remove old badges. I mean the metallic foil badges use on 1950-1970 machines, mainly Faemas.
I have tried several methods:
Goo Gone: The badge goes off nicely. Unfortunately so does the badge color.

Hair Dryer: The badge goes off nicely, but is twisted (rolled) afterwards and one cannot unfold it again. What I have done, I heated up the badge only a litlle tad with the hair dryer, and then used a very thin razor blade to remove it. Works fine.
Whenever it is possible, I would rather apply heat to the rear of the badge (ie the metal on which the badge is fixed) than to the badge itself. Gives the best results.