If corn oil comes from corn, and peanut oil comes from peanuts, where do baby oil and elbow grease come from? Sorry, couldn't resist.
Buy a floor scraper from your local hardware store. You want one with a fair amount of mass in the head, so when you hit what you're scraping, the momentum of the scraper will push through instead of bouncing off. This activity can be very hard on your elbow tendons, so be aware of that. Don't overdo it. If you are going to try any more solvents, make sure you use plenty of ventilation.