On the inside of the flywheel, you can use fine grit sandpaper, an emory cloth, or it should just wipe off. I typically put a THIN film of grease over the magnet to help fend that off, but that usually only happens once moisture has been getting inside there and I don't have that issue. I repeat thin. Like, dap your finger in some, wipe the finger clean with a rag and the remaining residue left on your fingers is what you rub over it.