Speaking of yielding, the headset should not loosen if you've done it right. If it embeds further, you didn't put it in right in the first place. The cups and crown race should be put on really hard. If you've ever done it wrong, bring it to a bike shop. Have them do it. If they're gracious, they'll teach you, too, so you know.

BBM, thanks for the tip on the tool. I'll put that on my wish list.