I haven't laid the bike down much or even ridden much the past few months, but yesterday after ripping around in a field with my friend popping wheelies I noticed this. At first I figured it was screws that simply came out from the vibration, but then I remembered that the end cap comes riveted into the silencer tube from the factory. I don't know how this happened, but all of them are gone, and the endcap isn't secured. Can you put new rivets in? If so, how?