Pook,Marx locomotives in some cases will not go threw Lionel switches.
They have what is called a fat wheel. It has to do with how the
gear is set up on the backside of the driver. This leads to some
Marx locomotives derailing on the plastic frogs of Lionel switches.
Yes, if you're not worried about keeping stuff original, Marx double reduction motors will go through just about any switch. Also give you better low speed operation and pulling power.Why not just get the engines that work?
I don't think a wheel exchange will work. Gearing may be different. Switching a motor is easier and you can use any switch.