Those are some sweet looking trains, I think the blue with the grey and white looms especially nice. Sorry I cant help with the front wheel issue, I only have one actual plarail train which is the 2 speed express train which my oldest son calls "mighty mac" lol
If you have some closeup pictures of the front axle maybe I could help a bit.
If you have some closeup pictures of the front axle maybe I could help a bit.