Here is what I used to do when I had my hobby shop. Run 45 minutes in each direction at varying speeds. Start moderate and increase periodically to higher (but NOT wide open) speeds. Reverse after 45 minutes and repeat. Check lubrication on axles and gears and lube as necessary. This is not doable unless you remove the shell and you may not want to do that. I tested each and every loco that I sold with a back and forth run of 5 minutes and ran break in on all Athearn, Atlas and the better Model Power HO. I simply tested train set locos and N scale. Roger
