After further tests, the champaign must wait:

When the actuator is cold, a strong immidiate force appears after power up - without the capacitor beeing powered.

When it´s warmed up, this imidiate force is not there, just the slowly rising force like in the pictures. I can´t tell where this strong froce is coming from, maybe an inrush shock on powerup?

The funny thing is that it stays as long as the power is on. On power-down it releases quickly to the previous value.