Andy, there is some seal that lets go and the fluid escapes, then the gears quickly chew themselves up. There is one Beamer entry in there with a half million miles, plus several others. No other bike brand has ever had a failure record like the final drives in the BMW's there were 17 FJR Yamahas, 13 ST1300 Hondas - never a drive failure. I have not seen it broken down to model years, but I'm guessing it is the 2006~2009 series. Why some do and some don't, could be faulty seals or a machining issue - something is definitely not 100%. It's a shame too as just like you and others (especially Jeff) this comes as a low-blow and shock.
I have a personal bias "against" the German imports, don't mind admitting it. We bought a new Mercedes in 2000 for the wife. That car has 92,000 miles on it today and has been in the shop twice as much as both of my Chevrolets trucks, purchased new which have a combined total of 350,000 miles on them. They tell you that 0 cost maintenance and 0 cost repairs for the first 50,000 or 4 years. Well, the first oil change after 50,000 was $269, and the first dealership complete service was $849! At 53,000 miles the mass air flow sensor went out - $597 and they refused to do it under waranty. The brake job requires that you replace the rotars and sealed bearings as complete units (they will not turn the rotors on these was $2,400). My 2003 Tahoe had 152,000 on it and the dealer called me to tell me they had a new steering shaft that would be a permanent fix for the original design - they installed it and gave me a free alignment.
I've been screwed enough, never again. Why do I keep it? I'm trying to run the wheels off of it and get back some of the high cost ot purchase and absolute outragous maintenance cost is why. I will never own one unless they just come out with something better than sliced bread.
I will give them credit for styling and innovations. They were the first to make ABS standard. Their licensed clothing is the best. They were first with heated grips and electric windshields - But all touring machines today made by the Japanese now have these necessities.
Sorry to make a mess of your thread Jeff - just want you to be up to speed.
Gordon