I haven't done this mod personally, so I have no experience with whether or not it's a good idea. But if you want to try it and have a backup plan, you can find replacement MagDrive parts here -
http://www.aqua-mart.com/show.pl?cmd...&subcatid=118.
The impellers aren't expensive. If you don't like the results of the mod, a repair won't cost you very much.