I use clear silicone adhesive for Litespeed head badges.
A thin coat covering nearly all of the back surface works well.
Permatex is the brand I have now.
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WTB: Slingshot bicycle promotional documents (catalog, pamphlets, etc).
WTB: American Cycling May - Aug, Oct, Dec 1966.
WTB: Bicycle Guide issues 1984 (any); Jun 1987; Jul, Nov/Dec 1992; Apr 1994; 1996 -1998 (any)
WTB: Bike World issue Jun 1974.