Originally Posted by HillRider

A Google check shows you are right. The HP-7400 was loose bearing but the HP-7410 was a cartridge bearing headset. I know the HP-6400 was loose bearing and HP-6500 is a cartridge bearing so I assumed the Dura Ace versions followed the same convention.

Anyway, I know that the HP-5500 (105) and 6500 (Ultegra) used the same "crown race" and think it's likely the 7410 used the same one. The instruction sheet that came with the 6500 also covers the 7410 so it seems likely they share a lot of parts.