c#中计时器的问题

所以我有一个计时器，每次它运行时都会改变图片框中的图像。我生成了一个随机数根据它是什么，它会停在那个图像上。因此，最初定时器工作第一次没有失败，它将停止在正确的图像没有问题。第二次它会出错，第三次它会在1秒后停止，第四次它会冻结。我不明白的是，计时器如何能第一次完美地工作，并停止(我认为会重置计时器)，然后第二次按下一个按钮，再次激活计时器，它就乱了?

下面是我的一些代码:

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Timers;
using System.Windows.Forms;
namespace WheelOfFortune
{
public partial class f : Form
{
    private static Random r = new Random();
    private static int spin = 0;
    private static int t1 = 0;
    private static int t2 = 0;
    private static int t3 = 0;
    private static int rn = 0;
    private static System.Timers.Timer st = new System.Timers.Timer();
    public f()
    {
        InitializeComponent();
    }
    private void Wheel_Click(object sender, EventArgs e)
    {
    }
    private void Spin_Click(object sender, EventArgs e)
    {          
        if (spin == 0) {
            t1 = 0;
            t2 = 0;
            t3 = 0;
            spin = 1;
            rn = r.Next(1, 53);
            Console.WriteLine("" + rn);
            st.Stop();
            st.Elapsed += new ElapsedEventHandler(OnTimedEvent);
            st.Interval = 15;
            st.Start();
        }
    }
    private static void OnTimedEvent(object source, ElapsedEventArgs e)
    {
        t1 = t1 + 6;
        if (t1 == 1)
        {
            Wheel.Image = Properties.Resources.Wheel_Test_0001;
        }
        else if (t1 == 2)
        {
            Wheel.Image = Properties.Resources.Wheel_Test_0002;
        }
        else if (t1 == 3)
        {
            Wheel.Image = Properties.Resources.Wheel_Test_0003;
        }
        else if (t1 == 4)
        {
            Wheel.Image = Properties.Resources.Wheel_Test_0004;
        }
        else if (t1 == 5)
        {
            Wheel.Image = Properties.Resources.Wheel_Test_0005;
        }
        else if (t1 == 6)
        {
            Wheel.Image = Properties.Resources.Wheel_Test_0006;
        }
        else if (t1 == 7)
        {
            Wheel.Image = Properties.Resources.Wheel_Test_0007;
        }
        else if (t1 == 8)
        {
            Wheel.Image = Properties.Resources.Wheel_Test_0008;
        }
        else if (t1 == 9)
        {
            Wheel.Image = Properties.Resources.Wheel_Test_0009;
        }
        else if (t1 == 10)
        {
            Wheel.Image = Properties.Resources.Wheel_Test_0010;
        }
        else if (t1 == 11)
        {
            Wheel.Image = Properties.Resources.Wheel_Test_0011;
        }
        else if (t1 == 12)
        {
            Wheel.Image = Properties.Resources.Wheel_Test_0012;
            if(rn == 2)
            {
                t2 = t2 + 1;
                if (t2 == 1)
                {
                    t3 = t3 + 1;
                    if (t3 == 4)
                    {
                        spin = 0;
                        t3 = 0;
                        t1 = 0;
                        st.Stop();
                    }
                    t2 = 0;
                }
            }
        }

代码在此之后相当重复，因为有624张图像要浏览，因为在开始时每次跳过6张，然后会逐渐变慢。(我还没有实现减速部分)。

我似乎看不到定时器不复位的原因，并再次做同样的事情，我错过了什么?

ResourceManager _resourceManager= Resources.ResourceManager;
...

 string _imageName=SomeLeftPaddFunction(4,"0",t1);//function to always pad to 4 0's
 Wheel.Image = (Bitmap)_resourceManager.GetObject("Wheel_Test_"+_imageName);

public class ImageCacheItem
{
    int Index{get;set;}
    Bitmap Image{get;set;}
} 
...
List<ImageCacheItem> _imageCache=new List<ImageCacheItem>();
....

Wheel.Image=_imageCache.Where(p=>p.Index==t1).FirstOrDefault();
if(Wheel.Image==null)
{ 
    string _imageName=SomeLeftPaddFunction(4,"0",t1);//function to always pad to 4 0's
    _imageCache.Add(new {Index=t1,Image=(Bitmap)_resourceManager.GetObject("Wheel_Test_"+_imageName);
    Wheel.Image=_imageCache.Where(p=>p.Index==t1).First();
}