satbuilder 

Colnago decals of that vintage didn't stick all that well, and weren't clearcoated. Could be the original owner stripped them off. The decals on my Mexico have been steadily peeling off.

Edit: the decal set available thru yellow jersey, on one sheet is enough to do like 3 bikes...supers, mexicos, and the early style. It seems expansive but you can use what you need and sell off what you don't.