I agree. Misfiring and burning points is almost guaranteed to be from a bad condenser. If you are getting a large blue spark when flicking the points, that will confirm a bad condenser.Arcing points is a sign of a bad condenser, replace it.
Back years ago, when I used to smoke, and rode bikes with points, I would use the strip on a book of matches to clean points. I don't see anything wrong with using really fine sandpaper on them, but only pull it through once, then flip it over and pull it through again. Besides a bad condenser, one of the big causes of points failure was poor contact between the 2 sides. I have seen points sanded or filed so much that only one tiny spot was actually making contact. I had to "dress" the points on my '66 Triumph Bonneville every thousand miles of so.Also, sanding your points down with sandpaper is one of the cardinal sins against ignition points. They do make burnishing tools for cleaning points, but those are tough to find at times.
http://www.cycleworld.com/2013/02/15/points-and-burnishing-files-tool-time/
Back years ago, when I used to smoke, and rode bikes with points, I would use the strip on a book of matches to clean points. I don't see anything wrong with using really fine sandpaper on them, but only pull it through once, then flip it over and pull it through again. Besides a bad condenser, one of the big causes of points failure was poor contact between the 2 sides. I have seen points sanded or filed so much that only one tiny spot was actually making contact. I had to "dress" the points on my '66 Triumph Bonneville every thousand miles of so.