Camera zoom has a yo-yo effect

I'm trying to make a camera with a scroll wheel zoom. I have it nearly complete, but whenever I zoom in, and then try to zoom out the camera bounces back in a few times before moving outwards. I think it's the value of the scroll wheel axis not resetting so it's still reporting a positive input? I'm not sure where I've gone wrong. Here's my code.

Any help would be greatly appreciated!

 using System.Collections;
 using System.Collections.Generic;
 using UnityEngine;
 
 public class ZoomController : MonoBehaviour
 {
     [SerializeField] Transform parentObject;
     float zoomLevel;
     [SerializeField] float sensitivity = 10f;
     [SerializeField] float speed = 30f;
     float maxZoom = 30f;
     float zoomPosition;
     void Update()
     {
        if(Input.GetAxis("Mouse ScrollWheel") != 0)
         {
             zoomLevel += Input.GetAxis("Mouse ScrollWheel") * sensitivity;
             zoomLevel = Mathf.Clamp(zoomLevel, -maxZoom, maxZoom);
             zoomPosition = Mathf.MoveTowards(zoomPosition, zoomLevel, speed * Time.deltaTime);
             transform.position = parentObject.position + (transform.forward * zoomPosition);
         }
         else zoomLevel = 0;      
     }