Clutch Pedal Problem
 

I've replaced my 2k 986's master and slave clutch cylinder. And I've also bled the system. (more than once) I've checked for leaks. Everything looks to be in order. However, the clutch pedal travel is acting weird. The top half of the travel is a spring-loaded klunk sound. The bottom half of the travel feels like normal clutch behavior. I have included a very short YouTube video link below that demonstrates what I'm describing. Has anyone seen this before? What could be wrong? I've bled this system multiple times. I've used a Motive power bleeder. At first, the full pedal travel of the clutch pedal would do this thunk sound, but then I noticed that it appeared there was a missing cotter pin on the nub on the end of the clutch return spring. I inserted a cotter pin in it and now I have the behavior shown in the video. Any ideas for me? Thanks in advance.

Upon further research, it appears that the cotter pin on the return spring is strictly used for spring removal. I will take it off. Nonetheless, the pedal travel has this big kerthunk sound and the clutch pedal doesn't feel hydraulic at all.

The clutch assist spring (that's what it is) may be broken. A fairly common problem.