Ian, the chain and sprockets actually look pretty good but the chain has some uneven stretch in it. I figured while I have the bike apart to change tires and with 21K miles on it, I might as well change the chain/sprockets at the same time.
I've always used Maxima chain wax (not heavily applied). I add a little every 500 miles and every 1000 miles I clean the chain (spinning on the bike) with kerosine and re-wax. At least once a year I remove the sprocket cover and clean away any build up. I usually don't have much due to the way I maintain it.
