Remove the LE15 and place it cone up, and see if it scrapes.
After removal from the cabinets, gently move the cone in and out with your fingers on both sides of the edge of the cone. Listen and feel for any rubbing or scraping effect. If not, move around the circumference and repeat. If not still, try gently pushing on just one edge to see if it rubs anywhere around the whole diameter, if not you have no problem with "centering" and your problem may be a possible loose voice coil? Those can sometimes become unglued and separate from the former and rattle loosly around in the gap...or something else causing noise. Have those units been recently re-surrounded? I had some LE15's from the early seventy's or maybe the sixty's and they had the Lans-a-loy type early white/yellow "foam" and they will be hard and brittle by now. I know you said the edges were fine, but I want to be sure. Have a great 2005! RE