fiber optic front sight replacement

I recently lost the fiber optic front sight insert in my Springfield XDm.

Springfield was kind enough to send replacements (enough material for 6 sights in 2 different colors).

Any suggestions on how to affix this to the sight? It fits but slides easily.

I'm thinking that I could enlarge the front end with a hot blade and put a spot of glue on the contact points or I could enlarge both ends with a hot blade.

Any recommendations?

DocAitch

fiber optic front sight replacement