It still has play even after making sure I tightened it down. The lock ring is definately tight. The rim is a 2006 Mavic Ksyrium SL SCC. The freehub looks great. No gouges or anything. It or the axle or bearings arent loose at all from what I can tell. I'm thinking songfta is on to something... I'm thinking the dork disk was acting as a spacer on my Korso/Titan/Neuvation. I'm sure I didn't leave out anything when I reassembled. In fact when I put on the cassette for the 1st time I moved everything over as a unit. The 2nd time I looked at each sprocket and spacer to make sure they were o.k. and I cleaned the crap out of them because I thought there was dirt or metal preventing tightening.

Where can I get the appropriate spacer for the Mavic wheels?

I moved my Korso's over to my gf's Trek 1000 8 speed and that cassette has no problem. Her Alex Rims AT 450's dork disc is attached to the spokes rather being wedged between the freehub and the cassette like my Ksyrium setup is.