Mainly I cleaned the field coil pickups where they stick out of the coil. I used a little fine grit sandpaper to "shine them up" Remember to clean off the surface of the flywheel as well again mainly the magnets, I again use a little fine grit sandpaper here too. To set the proper air gap between the coil pickups and the flywheel slip a business card between the coil and the flywheel then snug up the coil and remove the card all done. good luck