Don't pull your lens to pieces,,,send it to Nikon...Lenses are very delicate and complex piece of equipment..All you need to do is bump it,,put the elements out of alignment and you might as well throw it into the trash...

I have heard horror stories of people pulling their lenses apart and then sending them off to the manufacturer who will refuse to service them or charge an arm and a leg for a lens service which has been "fiddled" with by the owner..

Jurgen