So the chain was making a little noise when I turned the rear wheel by hand. I pulled the cover off the engine sprocket and found rust that did not make me happy. No grease and the sprocket was not clamped tight. Even though the bolt was tight the sprocket could float around on the shaft and there was some play on the splines. Interestingly both sprockets show wear on the inside(engine side) with shiny teeth. The spline wear was mostly on the sprocket, probably 90%, so that is good news. The new sprocket is snug on the splines. Everything cleaned and greased. I made a very thin spacer so the bolt and washer really clamp the sprocket in place. I suspect the left side chain adjuster was a couple mm farther forward causing the one sided shine on the sprockets. Front sprocket had 27,000 miles on it. Chain has 18,000 miles on it and shows about 1-1.5mm wear over 12" of length and has only needed adjustment once. I'll add check the front sprocket lube to my to-do list at tire changes.