Rich, I had the same problem with one of mine. I did manage to "cure" it with a couple of sheet metal screws, but I am unhappy about it. I called FFR and someone named Joe told me that they had had some problems with the interior piece coming loose and rattling around. Of course, they did not offer to replace my pipe even though it only had 600 miles on it, even knowing that they have a defective part. Typical on again, off again customer service at FFR. Back when I used to post often on the other forum this became a topic of dispute. There were those that even said I should expect this from "high wear" items with "600" miles on them. Hell, all it does is pass gas. My rectum has been doing that for 57 years and nothing is loose yet.
Frank.