As part of our efforts to reach the point that we can ship a device that consists mainly of robust, injection molded parts, we have been testing and evaluating concepts. Ideally we can eliminate problems by choosing the right materials, however there are also going to be some changes to concepts itself.
Here is the adjustment mechanism, which allows to adjust the position of the keys to the size of the hand/fingers. Main reason to introduce push buttons is that this way the direction of the force to lock/unlock the mechanism becomes different from the adjustment direction. This video shows the old mechanism and the new mechanism in action.