I'm having issues with an used Dura Ace 7800 Cassette I purchased. When I put all the pieces of the cassette on the hub of an older Mavic Ksyrium Elites, there is significant play and the threaded end cap does not actually screw tight against the cassette. I have tried an 105 10 speed cassette and it's fine. Even tried the Dura Ace end cap and it holds the 105 cassette tightly. Anyone know what could be going on here?