How to modify the value of an axis without touching to the others ?

Hi,

I'd like to animate the Robot Arm that comes with The Labo project when I press some key. The problem is that I can't figure how to move the arm part correctly, the body turn well but the arm doesn't follow the movement when I try do move it.

Here is the code: enter code herevoid Start () {

         body = GameObject.Find("prop_robotArm_body_001");
         arm =GameObject.Find("prop_robotArm_arm_001");
         
     }
     
     // Update is called once per frame
     void Update () {
         
         
         
         
         if(Input.GetAxis("Horizontal")<-.1){
             
             Quaternion targetAngle=Quaternion.Euler (new Vector3(0f,0f,0f));
             
             body.transform.rotation = Quaternion.Lerp(body.transform.rotation,targetAngle,Time.deltaTime*rotatingSpeed);
         }
         else if(Input.GetAxis("Horizontal")>.1)
         {
             
             Quaternion targetAngle=Quaternion.Euler (new Vector3(0f,180f,0f));
             
             body.transform.rotation = Quaternion.Lerp(body.transform.rotation,targetAngle,Time.deltaTime*rotatingSpeed);
         }
         
         if(Input.GetAxis("Vertical")<-.1){
             
             Quaternion targetAngle=Quaternion.Euler (new Vector3(0f,0f,-30f));
             
              arm.transform.rotation = Quaternion.Lerp( arm.transform.rotation,targetAngle,Time.deltaTime*rotatingSpeed);
         }
         else if(Input.GetAxis("Vertical")>.1)
         {
             
             Quaternion targetAngle=Quaternion.Euler (new Vector3(0f,0f,30f));
             
              arm.transform.rotation = Quaternion.Lerp( arm.transform.rotation,targetAngle,Time.deltaTime*rotatingSpeed);
         }
     }

and the result for now :