OK, y'all shamed (scared) me into it! I pulled the tranny back (snowbum method) on the ol' lady's '84, cleaned and greased the input splines. It was pretty much dry but no rust yet so I used one trimmed acid brush and lacquer thinner to clean and one to grease up the splines on the input shaft.
I guess it was due as the needle bearing assembly on the clutch arm pivot was pretty much frozen up. I was able to get everything rolling inside and re-greased it, the throwout bearing was fine and still well lubed and was the nice ball bearing type instead of the Torrington bearing...
I did a little experiment on the lube, I had used the BMW red #10 grease in the past but it seems to have fallen out of favor with all the "experts" lately. I have used Valvoline semi-synthetic wheel bearing grease for years, on both wheel bearings and steering head bearings - great stuff. I was rooting around for my tub of moly grease and happened to read on the Valvoline can that it contained moly so I gave it a try, we'll see in a couple of years how it held up. My thought is that since it's has a synthetic component maybe it won't dry out as fast, being a wheel bearing grease it's sorta sticky, and it has the moly component for wear resistance with the splines sliding against each other.
We're riding up to the Boxerworks Rally in a couple of weeks so I will at least have the peace of mind on the splines...
PLUS, the lathe sure turned out handy. I have a thin-wall socket that has fit every other Beemer I've tried it on except this '84 R65! I chucked it up in the lathe and shaved off a few thou and it now fit's great!