So you have some new track that works and some old track that does not work?
First of all, make sure the old track is electrically connected to your power pack. Assuming it is, then it sounds like the old track is dirty/oxidized and needs to be cleaned.
You can first try wiping down the track with a clean cotton cloth (an old t-shirt is good) moistened with a little alcohol. If that does not help, you will need stronger measures, as follows.
If you have a good hobby shop nearby, they might have a
Bright Boy Abrasive Track Cleaner. Rub the Bright Boy along the tops of the dirty rails. Do this on all of the old track.
If you can't get a Bright Boy, get some fine sandpaper, wrap it around a small block of wood, and use it to clean the tops of the rails. I would suggest something like 800-grit or finer sandpaper. If your local hardware store does not have such fine sandpaper, try an automotive supply store.
Use a light touch with the abrasive. You are not trying to grind away the rails, just remove the crud from the tops of the rails. After you have rubbed the dirty track with the abrasive, wipe it down with the cotton cloth and alcohol.
Normally, I do not like to use an abrasive track cleaner, but for really dirty, oxidized track, it may be the only way.
- Jeff