Vortex Sound Research

There's absolutely no google search sentence I've managed to come up with that makes the results understand what I want information on. Physical opening up of the insides of the synthesizer and from what I hear you can adjust how tightly the hammer weighed keys are screwed somehow, allowing you to make it harder or easier to physically push the key down with your finger. Does anyone know how to do that? Any videos that shows it? Anything? I own the Akai MPK88.