[vectorit]

I have good luck using these on various stuck on stuff.

Gum Out carb cleaner, and Goof off bug n' tar remover.

I'd start out mild, such as hot water and soap. Then, step it up gradually with various brushes and scotch brite pads.

When you decide to go with the harsh stuff, start out on a spot that is out of site.

I've also removed dried up glue like that with a fine wire brush on a drill, just go along very lightly so as to not damage the paint.

All depends on how dried up it is, crustier the better since it will flake off. If it's still gummy, then you are in for more elbow grease.