Quick correction, I drew the buzzer polarities in reverse. Positive should be negative, etc....
Actually, I can't be 100% sure which of the buzzer leads are + or -. All I know is that the BLUE buzzer wire is connected to the terminal which connects directly to the - battery terminal, and BLACK wire connects to the other one. I'm guessing the black was meant to be -.
I drew a little picture of the pcb. I hope you can make it out. To be honest, it doesn't look like the coil is connected to neither the - or +.
**broken link removed**
What kind of diodes would I need? Thanks Hero, you're a.....HERO! lol!