Go to harbor freight and get a couple jugs of "Evaporust". Best thing I've ever seen for what you're doing. Soak it and let the juice do the work. If you're patient it'll be slick as a bell pepper when you rinse it off.
Just picked one of these up at a model engine show in Lebanon, PA this weekend for $800 with 4 boxes of assorted wheels and a larger (manual) magnetic chuck. You and I lucked out!