I've just done a clutch job on mine, flywheel was in a bit of a state:
Used some 1200 grade wet and dry to take the glaze off the surface, you could feel the difference immediately. It went from glassy to matt - I wouldnt use anything quite as vicious as 100 range grade on it - you risk taking off too much material.
Just 'clean' it with high grade paper (600+) and a flat block, again I wouldnt use any power tools, just a bit of elbow grease. Been working fine since I did this to mine.