Any resolution yet ??
BTW :
When I first got my C-14 with 20K miles, I noticed when I rotated the rear wheel ( bike on centerstand ) I heard a clicking sound. I lubed the front spline on the driveshaft ( with moly paste, not moly grease ) and that eliminated the clicking sound.
The front spline wasn't dry but it didn't have much lube on it. IMO lubing the front & rear driveshaft splines should be a regular maintenance item. It's also an opportunity to check the driveshaft u-joints.
The squeak went away. I recall in the early days (07 or 08) reading on this forum or the other that people were hearing the click. There were also a couple reports of shaft bearing failures. Mine did not click but I went ahead and moly lubed my spline.