On my 07 DR650 with 12,300 miles I noticed some slop in the cush drive hub. If you grab the top of the sprocket with one hand and push towards the spokes and the bottom with the other hand and pull out away from the spokes and get a fair amount of movement it may be time to replace the six drive cushions. I took mine apart and looked at the seal in the cush drive hub and you could see that the double lips were wore down almost smooth. You could put thewheel spacer in and there was no drag from the seal. Which means it wasn't sealing like it should. The bearing in the hub is right behind that seal and doesn't have a seal of it's own on that side of the bearing. So any dirt getting by that outside seal is going right into the ball bearings. The bearing felt fine, but I bought a new one that is sealed on both sides anyway. So if you get a lot of play in the cushions it is putting a lot of extra force on that bearing in the hub and then it also wears out the seal. It doesn't really seem possible to me that there would be play if the bearing is still good, but there is. If you think about it when you tighten the axle it all becomes a solid piece. The left side head of the axle tightens up against the swingarm, spacer, inner race of cush hub bearing, spacer between cush hub bearing and left wheel bearing, spacer in wheel hub and right wheel bearing, spacer, swingarm and axle nut.
Here are a couple of pictures of an old cushion compared to a new cushion. New is on the right. The Suzuki part numbers are 09283-34003 for the seal, 64651-32E00 for the cushions x 6, and the double sealed bearing I got from a bearing house is an SKF 6205 2RSJEM made in USA.