If your window has the rattle the little white cap he found is usually all that needs replaced. If you look at his pics of the cap you will see there is a nub on the cap, when these get really worn it looks like theres nothing there but the roller when you look at it. If you stick a pick in the middle of the roller (side facing in the car) you can pop this piece out and then just snap the new one in and problem cured.