I recently picked up a 2001 Trek 2000 that is equipped with Shimano Tiagra STI Dual Control levers. There seems to be an issue with the right shifter. Just a note, this is my first bike with this style shifters, i've only had bikes with the twist style shifters at this point.

While riding the other day i went to change gears (to an inner gear on the rear) and when i pushed the lever in, it was very loose and had no tension as if the cable were broke. If i slightly apply the brake and attempt to shift, it then catches and shifts. This doesn't happen all the time.

I took it into my LBS a week ago and had them do a tune-up on the bike and i explained the issue to them. They said everything was fine, they couldn't duplicate the issue but they greased the shifter anyway.

Took the bike out again and it is still an issue. Any ideas on what may be causing this? Perhaps the shifter is bad or the cable has an issue?

Thanks