CW,
Thanks for that info up above. I've got a .04 washer that I'll cut a slot in a bit smaller than the axle. And yes.....I think it will be easier to get the washer on in the "well". And more importantly.....get it off it it goes South. That thickness washer should get rid of all of the extra slop in that wheel set.
Here's the link to the article.....interesting
http://cs.trains.com/ctt/f/95/t/88765.aspx
Roger