We are truly a blessed group to have such fine folk to share knowledge with. It's fantastic. So let me share a little. When I pulled the shaft out of my '86 K100RT (61,000 miles) I noticed the u-joint seemed to have a little notch at center. I'm thinking I better get this fixed or pay later. So I email Bruno's Machine Shop (up in the wilds of northern Ontario somewhere...the town is Iron Bridge). Johnny kindly suggests (see below) I call instead. Bruno doesn't do email. So my phone rang about 15 minutes ago and this friendly honest guy tells me the joint is fine. He explains that, due to a serration in the grease cups, it will feel like what I described. Further, that unless there is evidence of rust around the joint, as a result of no grease, moisture infiltration, etc., that I can expect another 40,000 miles out of it. I asked what a u-joint swap out would cost and he told me $200 Cdn.. I assured him that, when the time comes, my drive shaft will find its way to Iron Bridge for service. He replaces the OEM joint, where possible, with a joint with a grease fitting. In some models/years he has to put a Beemer joint back in. He can explain if you need him to. So a happy ending was had and I hope to begin re-assembly next week. I continue to be impressed with the quality of the parts that went into this bike.
PS - you cannot retrofit the OEM joint to accept a grease fitting....according to The Man!