Hi guys!

Just a quick and easy question... I have noticed an increase in vibration on my XT660r. When stripping down, i see that the chain has been polished on the outside facing links, top and bottom as if it's rubbing against something! On inspection i assume it's from the chain guides??? Also while checking that everything is secured and in good condition i notice that there is some play on my back sprocket! Is this right? Or is this a wheel bearing problem? There doesn't seem to be any play on the wheel itself! Any advise will be greatly appreciated!!!

Thanks in advance!!!