I would leave them be. Trying to touch them up could highlight them even more, and then you're looking at stripping and refinishing the whole handwheel.
That being said, some people have the skills to make a vintage machine look as though it just rolled off the factory line; and they look beautiful. I don't have those skills, so If I can clean them up, and get them running correctly then I'm happy.
How do you want yours to look?