So, how did the WD40 work? That would have been my suggestion. Sorry I am late. I have used WD40 on almost everything first. Gum remover, Stain remover, Lubricant, Rust preventer, Engine cleaner, Auto Detail restorer/beautifier, Flame accelerant, Deodorizer, Body wash, Cure for Cancer, and most important, World Peace enabler.
Great stuff.