It was this balling stopper: https://docs.google.com/file/d/0B9Oy...it?usp=sharing
so tight that the handle can't be push in and sit on the stopper:
Now it is fine, so fine that I can take it out easily, don't even need to pull.
Another update: The initial callbration showed that actual tension was 5-7 lbs higher. I strung first time yesterday, tension not adjusted. The feel was kind of werid. I did the calibration a few minutes ago, it takes about 5-8 seconds to settle and is near the reference tension. I am going to string another one later to see if it works.