heh, most people would be glad the buzzer stopped!
I hooked mine up when I restored my bike and I hate it but I've been too lazy to disconnect it.
You'll have to open up the headlight to check the wiring.
You can pull the buzzer off and hook it up to 12v to check it.
If it works it may be your flasher relay is going bad.
Replace it with an electronic one if it needs it..
If the buzzer is bad I'm sure someone here has one to sell or they show up on ebay as well.