My 2006 Street Bob has had an ever worsening rattle coming from the front of the bike for a year now. It sounds like a buzz or rattle at lower rpm's and is most noticeable when stopped at a red light. One night as my idle dropped sitting at a red light I noticed my headlight beam was bouncing on the car ahead of me. It would smooth out or get worse with a change in rpm, and the sound came along with the bouncing light beam! Some Dyna headlamps have mounts that are affixed to the headlamp can with 4 rivets. The rivets inevitably work loose. I drilled out 2 of the 4 rivets and replaced them with small bolts, nuts, jamb nuts and locktite. Buzz and bouncing headlight beam fixed!