Friend's going DCC

[woodone]

With the motor removed- you can reverse the two motor brush clips- top to bottom, bottom to top. Solder a wire to the clip which will go on the bottom, lots easer now than later like Lutz said. Be careful when you remove the brush clips, the brush is spring loaded and will fly apart if you are not careful. Also on the two trucks, solder a wire to each of the pick-ups that make contact with frame pivot point. This makes a better connection than the truck just touching the frame. If your loco does have sinter wheels you can replace them with a better quality wheel from several sources.
Remove the metal strip that makes contact with the trucks on the top side and make up a jumper so both trucks are hooked up by soldering the jumper to both trucks. Trim off any metal on each truck to clean up. Now you can install the decoder.