Paul sent in this helpful track cleaing tip:

Often the first indication of dirty track is a flickering locomotive headlight. My advice is to be careful when using any abrasive to clean your track. New track is generally nickel plated and you can often remove dirt without harsh abrasives. Once you remove the smooth coating with an abrasive, your track is exposed to oxidation and will need cleaning more frequently. The track will also be more likely to collect dirt. I use LaBelle #105 DCC Track Conditioner. Just clean your track with this product, and leave a micro-coating on the rails to dramatically improve your DCC reliability.