Ah. Found one at norvil.net. this looks unpleasant.
2010-09-04 13:17:03
9
shimano SIS road brifter assembly
Anybody know where I can find an exploded diagram of these? I've got one that moves but won't pull the cable 
and I can't figure out how it comes apart.
2010-09-04 12:56:11
Don't take apart before trying to spray it out with PB blaster or WD40 first. 9 times out of 10 it works great after soaking for 24 hours.
What kind of shifter are we talking about here? What is the age?
2010-09-06 22:58:15
Kiss it goodbye if the wd40 blast does not work.
Sram, you can use a small screw driver to remove a
plate and even an idiot (me) can tell exactly how
it works and can clean gunk out that stops it from
finding its clicks (what you have there)
2010-09-06 23:54:00
Er, STI, not SIS. Showing my age... It's an Ultegra 9-speed something-or-other. It finds its clicks. It just doesn't pull the cable.
Once I pulled it off the bike, I can see that it's clearly broken inside. It looks like there's a little plastic receptacle for the barrel on the end of the cable, and that receptacle has torn and the barrel has pulled through it. I can't push it back out, if I wanted to replace the cable. It's close to ten years old, low miles. Really annoying that some little plastic piece has failed and will cost hundreds of bucks to replace. This is what makes retro-grouches.
Sram sounds like a good alternative, if it's compatible (pulls the same amount of cable) with Shimano. I kind of like the flight deck feature. I wouldn't care on a single, but on the tandem it is hard to tell what gear you're in. Seriously considering bar-cons - do they route the cables under the bar tape?
2010-09-07 00:45:16
sram and shimano are not compatible. sorry.
2010-09-07 01:09:55
yeah, for barcons the cables go under the tape (and under the cable guides they supply):
I like them, although sometimes I think about STI - but a story like this is exactly what worries me about STI.
2010-09-07 01:28:34
Only Swiss watchmakers can repair broken Shimano brifters.
Seriously, you might try bringing it in to a shop. I've never seen this failure but maybe an experienced mechanic has. Can you push the cable head out with a small pick?
2010-09-07 21:14:10
I would not mind taking look. In my nearly 20 years of working on bikes I don't think I have seen that plastic piece break in a shimano shifter.
I hate to doubt your assessment of the problem but try soaking it in lots of WD40 or PB blaster for a day. It probaly will come back to life.
2010-09-08 01:07:44