Thank you, I'm glad I'm not the only one. I did check the basket and it seems to be clear of burrs. I set the release arm, on the clutch cover, a gear step further clockwise, as viewed from above, and adjusted the cable accordingly. That setting is much better. After about an hour of riding the grabby behaviour returns making it difficult to find neutral with the engine running.
It almost as if the biting point, as viewed at the clutch lever, moves slightly toward the handle bar after the bike gets warm. I was trying to think what could be changing to cause that. Such as the clutch plates swelling when warm or even the end float ( is that 'lash' in US parlance? ) of the gearbox input shaft somehow changing causing the basket to move relative to the clutch cover. I guess that might be influenced by gear selection. Looking at the drawing in the Service Manual I don't see a thrust washer or any specification for setting the end float.
I am contemplating replacing the clutch plates. But realistically the setting I have now is much better than it was.
Thanks - Ken