does anyone know how to tighten the mirrors on our bike between the stem and the actual mirror? my left one vibrates too much and its driving me crazy. i had an old one that had cracked glass, and when i took it apart there was a nut with a spring behind the glass that looked like you could tighten to stop the vibration. however, you would have to pop the glass out the mirror to tighten it and i dont think thats possible without breaking it. any advice would be appreciated, thanks guys!