After removing the bag from the emptor, turn it inside out and give it a good brushing/vacuuming first so you don't gunk up your washer.  Use mild detergent and warm water, not hot.  Hang the bag to dry, don't put it in the dryer.

The brushroll may be imbalanced (the ends not adjusted evenly) or it may just be shot.  The new replacement brushrolls with ball bearings are much better in my opinion, and you can even get them with 4 brush strips instead of just 2 which will greatly improve cleaning performance as well.

Machine buffing the metal will give the best results, particularly if there are deeper gouges/scratches.  I, and many others here have done it "the hard way" with pretty good success using metal polish and #0000 steel wool.  It takes a lot of patience, persistence and strong hands, but once that metal is gleeming again it's well worth the effort.

Btw, I love my D80 too!

Neil