A concave thrust washer(pictured above) holding the clutch basket must have been it.   I had the day off and went out for 100mi.  If I feather the clutch during my upshift to 5th, I can get it every time, and then it's off to the races.  If I grab full clutch, it won't engage. Bike runs fantastic otherwise.
I'm happy with it as-is.  Thanks everyone for the input over the past year.
fly out...