Hi Aussie Gregg.
My sons F800GS had a similar problem. The bottom of the ignition switch has a cam system that opens and closes a switch when the key is rotated.
It can be replaced seperatly so you don't need a whole ignition unit. We replaced the offending item and made sure the repalcement was properly water tight.
Check out UKGSer - the problem has been discussed over there several times.
Hope thats all it is.