I have a yamaha blaster 2000 200cc. the rear axle is loose. do i need new parts or can i tighten it?

the rear axle is loose and im not sure how to fix it. do i need new parts? or is there a way to tighten it up? in other words if i hold both sides of the axle with my hands i can shake it around/rattle it around whatever. even the sprockets and everything are pretty shaky but i just replaced those not to long ago. the quad has been ridden pretty hard so im pretty sure its just worn out. anyways any ideas on how to fix it??