CW,
I just now read an old thread in Classic Toy Trains Forum. Bunch of guys with 726s that had play in rear wheel pair. They used the method I considered.....cutting a slot in a washer. The thickness of it was ..04. Two questions.....they put it in the gear well.....between the worm and frame. Do you recommend that or putting it between the wheel and the frame? I'm thinking it's easier to put the washer on the axle in the well (or remove it if it doesn't work out). I also need the diameter of the axle so as to pick the right size washer I.D.