I can't say for certain Jon, but it's in the back of my mind from when I re-soldered the IPK buzzer on Oxfordblue's facelift 75.
His buzzer wasn't working (although he has factory reverse sensors), I know he looked into this and I had it in my head that this was the case - however I may have dreamt it !!!
Might be worth a post in the technical section, just for confirmation ?