It is staying up because he is holding the turtle up to show you the knock down target while taking the picture. The turtle body falls with the target when tripped. Come on guys.
Check to make sure the small delrin discs that hold the liner in place have not moved down the liner during shooting and are allowing the end of the liner to whip around too much and affect points of impact.
Can you try it without the felt or plastic extra baffle inside the different sections. Curious if the added volume helps. I pulled the felt from mine and it seems to work well, I just don't have a sensor to measure.