I pulled the cord about twenty times. And yes, my compression gauge has two check valves. One is at the beginning of the tube and the other is at the beginning of the gauge.
So, I think these two check valves (which has a spring) have some resistance. That is why I am having low compression numbers.

Also, I tested in two different ways. One test was done with choke closed and card closed. The other test was done with choke opened and card opened.
I got the same number.

Thank you very much.