| Hello mate, just had the same on mine, and found out that a Shim on the back of the sprocket was missing causing sideways movement which then started to wear the cush drive rubbers away, and i saw metal deposits on the swingarm, i also did the same and tightened up etc and still had the movement, got the shim replaced and no problems now, not good news but on the good side if thats what is wrong then the shim costs next to nothing
Hope that helps
Cheers
Rob | 
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