Tempest has decals for sideart, and therefore you could restore it with 3M. Somebody in this forum (or in the project announcements one) posted his experience Mame'ing his tempest and he described his sideart as decal-type, rather than painted. Do a search and verify that this is the case. Defender, Gyruss, Pacman, MsPacman, etc. are painted, so recovering the underlying art is tougher, but still possible; however, I've never seen a 100% restoration on painted cabs. Most likely these people recover just enough of the original art so that they can repaint it. Fortunately for you, tempest is not painted.