I'd stop using that mail polish remover if I were you. The plastic on these vintage buggies are made of styrene if I'm not mistaken. Nail polish remover is acetone. Actone melts styrene!

You can try using old brake fliud to remove the old paint which is usually hobby grade enamel. You have to soak the parts in a glass or plastic bowl for about 1 hour to soften the paint. I've used that method effectively on some of the Monster beetles I've restored.