[tomy]

one way that i coded our arm is this

 if(leftstick.getrawbutton(2)){
                   vicelbow.set(leftstick.getY())
            }

this way when you press and hold the button the victor that controls the elbow will move based on what your leftstick is doing

but then again we are using a xbox controller for our driving and a two joysticks for our arm

hope it helps