Stampede transmission help

[nastety92]

I have an older style stampede and I've just replaced all of the internal transmission parts and upgraded to the newer style stampede slipper clutch, RC Monster Aluminum/steel differential and steel idler gear. When everything was back together I found that shaft that the slipper clutch is on is loose, it will move up/ down and in/ out only a little bit but enough where I'm sure it will be a problem once I start to run the new 5700MM setup. What did I do wrong?

Thanks,
Nick