You can also use a fine - med/fine flat stone (sharpening stone) preferably a new one and lightly polish the surface, just let the weight of the stone do the work and move the stone evenly over the entire surface, use it with WD-40 or like and when finished clean the surface with carb cleaner or acetone.

Works the treat!

Chucky MoMo <img src="/forums/images/graemlins/wink.gif" alt="" />