So I'm in a serious horn problem. I'm playing in the competitions at ITEC next week, and have come across a serious problem with my instrument. I play a Kalison DS, which has a valve-set which is connected to the horn with 4 screws located along the bell and outside bow. Each screw has a circular rubber guard that stops vibrations in each screw hold.
After several years of using the guards, I've run out. One of the guards has torn and came off. my horn rattles quite loudly when I play in the middle range.
Any suggestions on how to fix it? Can you buy rubber guards at any hardware store? I'm freaking out right now, and any help would be greatly appreciated.

