So, i was attempting to setup a shimano 105 (5600)front/left shifter. At some point as I was messing with it, it stopped working. It still pulls the cable through when you operate it, but it doesnt click now. From the small cog, i can push the lever and shift it up to the big one, but as soon as I let go, the derailer drops back down to the smaller one. I disconnected the cable from the derailer and worked the shifter and it doesnt click at all. Its like the ratcheting mechanism inside the shifter broke. Is this repairable in any way, or is a replacement the only way?

Thanks

I did the same thing to a 6500 left shifter 5-6 years ago.

It was an expensive mistake in a month when by budget lacked any slack.

If it's new send it in on warranty. If it's not new try a big shot of WD40 straight into the mechanism.

Yeah, its pretty much new, but I bought it on ebay - it was a take-off from a mostly new bike. The mechanism turns very freely and shifts smoothly (as long as I hold it in position and dont let go of the shifter when going to the big cog).

Apparently the double shifter is similar to the triple and can get spun past as if it were going for the 3 sprocket. Hopefully, there is a way to get it back around without permanent damage. I can tell that is what has happened because when I hit the shifter to get it to go to the small cog (doesnt really do anything though) and pull the brakes to look inside, I can see that the mechanism inside hasn't returned back around to the position it was in when I threaded the cable into the shifter

Well, I sought professional help at the LBS. They took it apart and found that a metal tab the supports a spring was snapped. Luckily, the gruppo was basically new and very cheap, so the loss isnt too bad.

My next build will be DT or BE shifters. I have a nice setup with 105 brifters, but I just am getting to the point that I enjoy riding my old '80s steel frame with friction DT shifters as much. I would be mucho POed if I had a minor crash that took out a brifter, or worse yet, it just quit working. (retro grouch coming out.. ;-) )

My son crashed and broke one 105 brifter. The LBS had the correct one in stock.
We didn't have to purchase a pair. Maybe your LBS can order you just one.
It will still be a pain in the pocketbook, but less than purchasing a pair.