The Seaboard's playing surface is very sensitive, and its maximum expressive potential is reached without significant force or manipulation. It does not respond to being pulled or pushed from its resting position.
If you're not sure how hard to press, open up Equator and watch the Press box when you play a keywave. You'll be able to see how much pressure is needed to reach the top, which is the maximum value available.
It's also possible to adjust the Seaboard's responses in ROLI Dashboard.