Wiring the dual-motor Williams locomotives in series to slow them down and prevent "jackrabbit" starts has long been a controversial topic, and more than once has caused me to think twice about doing the mod to my Williams NW-2 switcher.
Well, I am now saying, "Don't knock it until you try it, and you can try it without cutting any wires or making any permanent changes!!!" Here's how you do it:
1. Remove the shell, and cut off the zip tie that is securing the wiring.
2. Carefully separate the jumble of wires, and unplug both motors from the main board.
Here's the key: The wires can be removed from the Molex plugs with their ends intact! Simply lay the connector on a hard surface with the slots up, and use a small flat screwdriver to CAREFULLY mash down the little "barb" that is holding the end in the plug and pull gently on the wire. It takes a little finesse, but it will come free with some patience.
3. Use the above technique to remove the BLUE wire from the cab end motor plug.
4. Use the above technique to remove the BLUE and YELLOW wires from the hood end motor plug.
5. Insert the BLUE wire from the hood end motor into the cab end plug.
6. Reinstall both plugs in the main board. It really doesn't matter which one goes where, but you did remember where they came from, right?
You now have a blue wire from the cab end motor, and a yellow wire from the hood end motor that need to be connected together.
7. Slip a piece of shrink tube over one of the wires.
8. Obtain a short piece of conductive metal (copper, brass, steel) that fits tightly in the wire ends. I used a cutoff wire from a Radio Shack 276-1181 rectifier that I had left over from another Williams slowdown mod. Any stiff wire the right diameter will do.
9. Cut a 5/16" long piece of the wire, and use it to connect the blue and yellow wires together.
10. Slide the shrink wrap over the connection, and shrink it.
11. Fold all the wires back down and secure with a new zip tie.
12. Test the locomotive, then replace the shell and have fun!
It's all reversible. All you have to do is cut off the shrink wrap, and put everything back the way it was if you don't like it.
Frankly, I like the results. Top speed is still fast, but not crazy fast. It will just barely creep along, which is absolutely awesome.