Powertap freehub is loose, and I don't mean slutty

Not happy! I've been without the luxury of the Powertap data for about 3-4 weeks. Having also been without a rideable cross bike since last winter, I needed a wheel that I could throw on the cross bike and get it ready to race. I even bought a pair of Michelin cross tires and tubes and a new chain.. So I get the Powertap wheel off the road bike, intending to put it onto the cross bike for a while, when I discover that the freehub/cassette has 2-3 mm of lateral play in it! How the F did that happen? I don't even own a tool for removing the cassette so I can't really see what's going on in there, but when I move it out as far as it can go, there's quite a bit of daylight between the granny gear and the hub body. It's a miracle that I was ever able to shift gears properly these past few days or weeks. So I'm still without a rear wheel for the cross bike. The original wheel has three broken spokes and a seized up freehub. The Powertap wheel needs to be rebuilt or replaced as well. The only way to get me on a cross bike this winter, it seems, is to somehow change my tubular Rolf Vector Pros, from Campy to Shimano, and I don't even know how. From what I've heard, the RVCs make excellent cross wheels. I've owned mine since 2003 and they turned out to be an excellent pair- still as straight as when I bought them. So maybe I exchange the Michelins I bought for a pair of cross tubulars? Ah! What's the point. All this trouble and expense for two or three cross races and near certain DFLs.. Maybe someone will loan me a decent Shimano rear wheel.