Mate , i would let your Dealer know what you have found. I had the same experience, my spline was rooted though. A mate at a Triumph Dealership went through every directive back to 2006, Triumph has ' never ' told their techs to grease that spline. It is not mentioned on any ' sceduled service ' so it is never done. After finding these facts out i contacted Triumph Australia. They replaced the driveshaft ( i've got a spare now ) and the spline in the diff under warranty. At the time mine stuffed up i was actually a couple of months out of warranty. I had done a lot of miles in the first 2 years but they still came to the party .. after a bit of shoving. Like i said i grease mine every time a get a new back tyre now.