Fongstarr, is it a digital sound going off or the actual sound of what the flash tube would make? I don't know too much about flashes, especially the hardware inside, but maybe the actual bulb (wire?) connection is bad.
For anyone into street photography, there's a pretty good documentary on photographers like Bruce Gilden, Jill Freedman, Boogie, and others. It's a pretty good watch, at least worth the $5 rental. For me, stuff like this is a good resource to pysch myself up if I'm going out to shoot street.
http://everybodystreet.com/