How to freeze movement on X-axis. (See Comments for Update)

I’m putting the finishing touches on my Pong clone but I am unable to change the enemy’s speed once I set him to follow the ball’s position.Y

First things first, im trying to get it to listen to the speed variable change

Second I’m looking for a point in the right direction as far as getting the enemy to change his speed depending on the speed of the ball.

Here’s my code: C#

using UnityEngine;
using System.Collections;

public class NewEnemyAI : MonoBehaviour 
	public float yMin, yMax;
	public Transform target;
	public float speed;
	void Update () 
		float inputSpeed = Input.GetAxisRaw ("Vertical");
		transform.position += new Vector3 (0, inputSpeed * speed * Time.deltaTime, 0);

	void FixedUpdate () 
		rigidbody.position = new Vector3 
			 Mathf.Clamp (target.position.y, yMin, yMax),

I think that in the Start function you should define your “speed” variable to be the velocity of the ball. Something like:

speed = GameObject.Find(“ball”).velocity

Then the variable would be a reference… I think… to the ball’s velocity. If I’m wrong and that line only fetches the current value, then you could have a reference like:

GameObject ball;

Then in Start:

ball = GameObject.Find(“ball”)

And then whenever you need it, reference “ball.velocity” which is a Vector3.

So i ended up using a vector3.movetowards method and its working great except I cannot get the enemy paddle to freeze on the X-Axis. I tried clicking the freeze X position in the rigidbody component but since my code is in the update function it overrides it I guess. Any help on code for freezing X-Axis movement in the update function?

using UnityEngine;
using System.Collections;

public class EnemyMove2Ball : MonoBehaviour {

	public Transform target; // drag the player here
	float speed = 5.0f; // move speed
	void Update()
		transform.position = Vector3.MoveTowards