Vibration inside muffler

I had my muffler off a last week and it rattled a bit in my hands. I observed there were something like a series of disks inside, which rotated about a common shaft. I was able to move one of the disks and that eliminated any more rattling...for a few days. Now it really makes a lot of noise when riding. Is there a proper way to tighten-up the muffler innards?

Thanks!

Everything else is working well with the engine, which is great since I use it go get back and forth to work, even if it's 30 deg. outside!