Yes, put some clear scotch tape and it fixes it with no effect of results.
I got some at TMEA this year for the mouthpiece to lead-pipe connection. I have mixed feelings about them. The first thing I noticed as several have stated is the boost in feedback. I also noticed what seemed to be a boost in the focus of the tone. Articulations are clearer with the same effort, and range was more even but added more resistance, similar to what happened when I added the heavy weight caps to the horn. This was good to a point, and then I started building my endurance up tp a higher point and they became almost unusable for my setup. Maybe it would work if I was using a more open mouthpiece with less focus, IDK. But even when I was using it and I play tested them in the recital hall after a dress rehearsal, I noticed little to no difference in the quality of the tone I heard, but it was less flexible and less vibrant of a sound. It also seems to make my sound quieter. Upper register requires much more effort. Low register is more projecting, but restrict the range.
So to sum it all up, I got a lot of technical advantages from it, but as soon as you want to be expressive, it makes it harder to do so. It makes everything sound kinda generic to me. Keep in mind I'm playing an ADAMS and the adjustable receiver may be causing it not to work as well.
Adams E1 SS, Gold Brass Body .6mm DE Euph N103 Jcup, J9 shank
Meinl Weston 2141 Eb Tuba PT 84