I have heard of power wire brushing will de magnetize the magnets or change their polarity. I even a had couple coils to fail over the years that work one day, lightning storm comes through and the next day they don't work.
Really the flywheel magnets needs only a light cleaning as magnetism is not affected by rust, just creates a clearance issue.
It's good to know this AVB a out saves needless pedantry when sanding them clean. Just make them reasonably smooth and you're set!
