Question about partial piston stroke

[itsme]

My team wants to make a partial stroke.
What I mean is the following:
A joystick button is pressed-->piston starts to open
Another joystick button is pressed while pitons opens-->piston stops.

How do we do that?

We have tried to put another single solenoid after the main double solenoid.
It partly worked: when we pressed the second button, the piston stopped, but then started to come back slowly.

We are trying to do this to prevent the smack of the piston on the robot (it raises an arm).