Bummer FairJack. Fortunately, I didn't use my Blades enough to develop any knee issues. The rocking problem was so bad I removed the pedals from the bike right away.
Wouldn't expect much help from Look USA. Just got my two sets of Blades back from them after many weeks of the usual corporate delays and stonewalling. A new Look warranty department hire eventually took one set out for a lunchtime spin, pronounced them a-ok, and sent everything back to me. Think that's the only attention my pedals ever received.
Don Lamson at D2 now has the pedals and my D2 shoes. Slim chance the curvature of my D2 soles is off and doesn't match the curvature of the Blade cleats. (If so, the cleats would distort when screwed down and not mate properly with the pedal.) But there's no rocking or looseness using my Dura Ace pedals and cleats with the D2's, and I also had the same results with my Sidis—solid on the Dura Ace, rocking on the Blades—so kinda doubt shoes are the issue. Will let you know what Don has to say in any case.
Got a bad feeling I'm gonna have to dump some new Blade pedals pretty soon.