Do you have a physical sample of this mechanism?  If so you could instrument it to measure the vibration at the red mark or the piston.

What is the significance of the red mark? Why does it matter if there is some vibration at that location?

Why is the red mark at the end of a short offset beam?  That short beam seems like it could amplify the vibrations of the piston. Can the beam cross-section be larger?

What causes the piston to move, fluid pressure? What is the fluid? How is the fluid pressure controlled?

If the stick-slip motion is a problem, why not use an actuator that has no stick-slip behavior such as a bellows arrangement.

What are the requirements for the motion of the red mark? Does the actuator have to use a fluid at all, could it be a done with an electro-mechanical actuator?