Tough call where to post this - kind of a technical scratching and bashing, done to Z scale but can work on other scales. Just won a Marklin Z scale Freight Starter Set. Comes with one 0-6-0 tank loco and a 2 axle freight 'wagon'. The locomotive electrical pickup is only on 4 wheels and it stalled regularly at slow speed below 30 scale mph. I'm very picky about prototypical speed performance, especially a steam loco - i like to see the drive rods slowly pumping back and forth, not just a visual blur. And i really hate having to reach out and constantly nudge the locomotive whenever it decides to stall. So decided to convert to 8 wheel electrical pickup using the metal wagon wheels. Now it runs at 1.2 scale mph on 30 Hz 8V pulse without stalling. Here are some photos showing the basic technique. One of the things that really helped was the truckless wagon wheels - since they don't swivel it was easy to add wiping contacts to the wheels. The wipers were designed for the Micro-Trains Z scale F-7 to prevent similar stalling, but they just happened to fit nicely into the wagon. They look ugly, but can't be seen in normal operation when the wagon is viewed from the top or side.