右にある画像を左に移動させたいです。

HTML
1<html>
2  <head>
3    <meta charset="utf-8">
4    <title>マウス君</title>
5    <style>
6      #img2 { position: absolute;
7      right:10px;
8      bottom:1px;
9      }
10      
11    </style>
12    <script src="mousekun.js"></script>
13  </head>
14  
15  <body>
16  <p><input type="button" value="実行" onclick="mousekunMove()"></p>
17  <p><input type="button" value="停止" onclick="mousekunStop()"></p>
18  <img src="imgM1.gif" border="0" id="img1" style="position:absolute">
19  <img src="imgM2.gif" border="0" id="img2" style="position:absolute">
20  
21  </body>
22</html>

javascript
1var timer1,timer2;
2var i;
3
4var imgLeftStart = 0;
5var imgLeftEnd = 500;
6var imgLeft = imgLeftStart;
7var imgTop =100;
8var moveStep = 5;
9var moveSpeed = 100;
10
11
12
13//マウス君の移動
14function mousekunMove() {
15  timer1 = setInterval("rightMove()", 50);
16}
17
18//マウス君の停止
19function mousekunStop() {
20　    clearInterval(timer1);
21　}
22　
23　
24//右に移動
25function rightMove() {
26
27 imgLeft += moveStep;
28 
29 if(imgLeft > imgLeftEnd){
30    imgLeft = imgLeftStart;
31 }
32 
33 document.getElementById("img1").style.top = imgTop;
34 document.getElementById("img1").style.left = imgLeft;
35}
36//左に移動
37function leftMove() {
38
39 imgLeft += moveStep;
40 
41 if(imgLeft > imgLeftEnd){
42    imgLeft = imgLeftStart;
43 }