Should there be any noticeable movement of the rear axle in a side to side or up and down movement within the carrier bearings?

 

On the sport quads there shouldn't be any "noticable" play. There will be a couple thousandths but not real movement. On a 400ex for example you will get 2 maybe 3 years out of those bearings. If you think they are bad they prolly are.

 

I had a Polaris Trail Boss that had play. When I toke it apart the old bearings had no more play than the new ones. If you can turn the nut in it will tighten it up so you don't have any play. The nut on my axle was so tight I ended up ruining the nut so I had to replace that as well.