One more tip I got from the BF community- I had an aluminum bike, and once I was taking the rear wheel off, and I couldn't get the wheel back in- I tried for hours. As it turns out, Waldo and Mech (I believe) told me that with aluminum bikes, sometimes the chainstays move a little closer together when you take the wheel out, so you may have to use both hands to pull them apart as you drop the wheel back onto the bike. So if the wheel doesn't drop back in easily, that may be one solution for you to try.

Koffee