[Doodlebug]

Maybe someone will have a better suggestion so please wait and see. But I know that Skin So Soft bath oil from Avon will take hardened road tar off of a car and it will remove the sticky goo from store tags from glass things.

If nothing else, maybe you could try putting some on a cotton ball and try to work it out. I would wait to see what others suggest first though. Maybe there is a proven method that works great. Good luck.