I have a used 2011 trek 1.2 compact road bike with a stiff Sora FD-3400 double front derailleur.
Shifter seems very stiff, and when I shift above the second index (trim or third) by accident it gets stuck on the big chainset ring and then it takes a huge amount of force to release it or even impossible and I have to release the shifter cable from the derailleur. As I understand I should set the top limit so it won't go over the second index right? But even if I shift to the second index and try to lower to the first it takes some heavy force and there is a loud clank when it does get released.
I think its the derailleur because when I detached the derailleur, pulling the cable in the housing seems smooth, and the shifter has good and smooth pull and release for all its indexes and trims.
Here's a video of me pulling hard on the cable
Here's my video of how hard it is to move:
Compared to what I see here at 1:34 mark:
when it does shift this is the sound it does at the end of this video (not my video)
I also suspect the previous owner had something to do with it, since there is a little dent under where the derailleur clips shown here:
Am I right thinking its the derailleur and should replace it? What else can it be that I should check?