Badly pitted Distributor Cap contacts

I have had a bit of a shake at idle for a short while now. After removing the distributor cap I noticed that nearly all the contacts are badly pitted and rusty in nature. I attempted to clean them up with a wire brush, with little success. It appears the contacts are now below the level of the plastic that supports each one where to rotor contacts it. I also cleaned the rotor with a bit of sandpaper. I still have the skake at idle. At higher revs I notice no shake, of course, and no loss of power or performance. I did replace the plugs, not the wires. Plugs are gapped at .032". Car is an 89 420SEL with 161,000 miles. Should I replace the distributor cap and rotor? Is it possible that all my sanding and brushing has made the situation worse via wider gaps? Any help will be appreciated.