Thanks to all for this thread. Years ago I came here and Robert the Honda guy advised me just to clean and lube that plastic bushing. Worked for only a short while. I noticed he has since vanished from sight. I am now tuning (3) HRR216VKA's (my 10yo, and 3yo, and the neighbor widow's) so I returned to find out how widespread this issue is. My neighbor had completely worn out her rear tires this year. I basically solved the problem by always cutting my grass is circles, and not backing up much.
Hopefully this thread comes back to life when the weather warms up. Love to hear how all the solutions endure, and make some necessary modifications.