Here are a couple of links that should help you...if you want to try it. Funny because I'm actually taking a break right now from overhauling a set of 8 speed 600 shifters. Finished the right lever and it's working like a charm. I have the left lever broken down and parts soaking in degreaser. As stated above it's almost always sticky pawls that are the issue. I haven't tried 9 or 10 speed yet though.
http://www.nitrodyno.com/Ultegra-STI/
http://www.norvil.net/pedal/service/...osti/index.php
The 'next page' link is at the bottom of the page. There is a section for Dura Ace and Ultegra.
Also, this guy has some good info and services for 7 & 8 speed stuff if you don't want to do it yourself. He doesn't fix 9 & 10 speed shifters though.
http://www.facebook.com/group.php?gi...6572916&ref=mf