How to swap front number boards on Porters?

[Flare]

My goal is to re-number on one of my Porters.

I tried removing one from a dead loco in my parts bin but it snapped off, and I suspect the base is glued in place because I can't push it out from the other side.

Is there a way to get the boards out without breaking them, or any solvents for the glue that won't affect the paint?