Problem with assembly constraint.

Hello,

I am in the process of designing a push switch.

The function of push switch is simple. There is an arm rotating on a hinge, the push button slides over the arm's surface and the push button slides inside the hole. As the arm returns the push button also returns. My problem is that I am able to rotate the arm, slide the arm over the push button surface and move it inside the hole. But, as the arm rotates back, the push button will not come to the original position. I have attached the images below.

Also, my animation for the same design is not working. I gave a servo kotor to the hinged joint(pin) of the arm. The arm doesn't move at all in the animation

Expecting an answer.

Thanks,

Vignesh