I will try not to cut mine in half when I do it. Should be simple enough, just need some new gaskets as I have a slight leak from cylinder 2 and 4.

Panda is right with the voltage, 11.4 sounds low. You would expect 12v rising to mid 14v when reved at 4000rpm if its staying low or dropping when reved it will point to the reg/rec.

Right okay then, I will try that in a little while. If the rectifier has gone, could it damage my bike from starting and running it?

I am not good with electrics would say under charging shouldnt cause any damage but over charging will boil the battery.