"The "Columbus" tubing foil sticker on the downtube above the shift levers is curled back at one edge . . ."
Bill,
Back in the vintage day, all decals were glued down with varnish that's officially known as "gold size." The stuff is available in arts supple stores. There are two formulas; one that dries quickly and the other call "slow" drying, which gives the greatest durability. It should be applied, very thinly, to the back of the decal and allowed to almost completely dry. After the recommended drying time, touch the glued surface with your knuckle (or some hard plastic). When you pull it away it should give off a sound like "snap" or "click," the decal is ready to be pressed down. If you're unsure, ask someone who has worked with gold/metal leaf.
Michael Allison
New York, NY