Why doesn't the third part of if statement work?

I don't understand what's wrong..

Trying to do a very simple slot machine and can't figure out where's mistake.

And I need to check if it's 3 pikachus - add to amt 1000, but if it's 3 charmanders - add 500. "amt" is a current amount of coins. At the beginning it's equal 100. Every attempt costs 10 coins. Can someone give me some ideas?

enter image description here

var slotitem = [];
slotitem[0] = "slowpoke";
slotitem[1] = "snorlax";
slotitem[2] = "squirtle";
slotitem[3] = "bulbasaur";
slotitem[4] = "charmander";
slotitem[5] = "picachu";
var coins = 100;
var arm = document.getElementById('arm');
arm.onclick = function(){
  this.classList.toggle('rotate')
    //this.style.height = '200px';
    //this.style.width= '100px';
};
/*arm.onclick = function() {
      var start = Date.now(); // сохранить время начала

      var timer = setInterval(function() {
        // вычислить сколько времени прошло из opts.duration
        var timePassed = Date.now() - start;

        arm.style.top = timePassed / 7 + 'px';

        if (timePassed > 1000) clearInterval(timer);

      }, 20);
    }
*/
///////////////////////////
slots.txtCoins.value="100";
///////////////////////////
function rollem() {

  counter = 0;
  spinem();
}

function spinem() {

  turns1 = 6 + Math.floor((Math.random() * 6))
  for (a = 0; a < turns1; a++) {
    document.slots.slot1.src = "" + slotitem[a % 6] + ".png";
  }
  turns2 = 6 + Math.floor((Math.random() * 6))
  for (b = 0; b < turns2; b++) {
    document.slots.slot2.src = "" + slotitem[b % 6] + ".png";
  }
  turns3 = 6 + Math.floor((Math.random() * 6))
  for (c = 0; c < turns3; c++) {
    document.slots.slot3.src = "" + slotitem[c % 6] + ".png";
  }
  counter++;
  console.log(counter);
  if (counter < 25) {
    setTimeout("spinem(counter);", 50);
  } else {
    checkmatch();
  }
}

function checkmatch() {
  var amt = parseInt(slots.txtCoins.value);
  if (amt != 0){
        if ((document.slots.slot1.src == document.slots.slot2.src) && (document.slots.slot1.src == document.slots.slot3.src)) {
      
      amt = amt + 1000;
      slots.txtCoins.value = amt;
    } else if ((document.slots.slot1.src + slotitem == 0 == document.slots.slot2.src + slotitem == 0) 
               || (document.slots.slot1.src + slotitem == 0 == document.slots.slot3.src + slotitem == 0) 
               || (document.slots.slot2.src + slotitem == 0 == document.slots.slot3.src + slotitem == 0)) {
      
      amt = amt - 10;
      slots.txtCoins.value = amt;
    } else if ((document.slots.slot1.src == document.slots.slot2) 
              || (document.slots.slot1 == document.slots.slot3)
              || (document.slots.slot2 == document.slots.slot3)) {
      amt = amt + 100;
      slots.txtCoins.value = amt;
    } else if ((document.slots.slot1.src != document.slots.slot2.src) && (document.slots.slot1.src != document.slots.slot3.src)){
      alert("Попробуйте еще раз!");
    }
  }
  else
    alert("Кажется, у вас закончились монетки. Удачи в следующий раз!");
}

/*function checkmatch1(){
  var amt = parseInt(slots.tstCoins.value);
  var slowpokes,snorlaxes,squirtles,bulbasaures,charmanderes,
    picachus;

    slowpokes=0;
    snorlaxes=0;
    squirtls=0;
    bulbasaurs=0;
    charmanders=0;
    picachus=0;
  if (amt != 0) {
    for (x = 0; x < 3; x++){
      switch(){
        case "slowpoke.png":
          slowpokes++;
          break;
        case "snorlax.png":
          snorlaxes++;
          break;
        case "squirtle.png":
          squirtls++;
          break;
        case "bulbasaur.png":
          bulbasaurs++;
          break;
        case "charmander.png":
          charmanders++;
          break;
        case "picachu.png":
          picachus++;
          break;
      }

      if (picachus == 3){
        amt = amt + 1000;
      }
      else if(charmanders == 3){
        amt = amt + 500;
      }
      else if(bulbasaurs == 3){
        amt = amt + 300;
      }
      else if((squirtls == 3) || (snorlaxes == 3) || (slowpokes == 3)){
        amt = amt + 100;
      }

   }

  }
}

*/

body{
        background-image: url(pics/backpic.jpg);
        background-size: 100% 700%;
}
h1{
        font-family: 'Luckiest Guy', cursive;
        font-size: 50px;
        text-align: center;
        color: #F5DA1C;
        text-shadow: #5F7DC4 3px 3px 0, #5F7DC4 0px 0px 0, 
                 #5F7DC4 0px 0px 0, #5F7DC4 3px -3px 0;
}
img{
        width: 100px;
}

#square {
        position:absolute;
        left: 215px;
        top: 200px;
    width: 370px;
    height: 180px;
    background: #5F7DC4;
}
#roundsquare {
        position: absolute;
        width: 400px;
        height: 310px;
        top:150px;
        left:200px;
        background: #9AC1DA;
        border-radius: 50px;
}
#squarebottom {
        position: absolute;
        width:450px;
        height:100px;
        top:380px;
        left: 175px;
        background: #9AC1DA;
        border-radius: 30px;
}
#linearm{
        position: absolute;
        width: 70px;
        height: 10px;
        background: #BDBDAD;
        left: 600px;
        top:280px;
}
#linearm2{
        position: absolute;
        width: 10px;
        height: 70px;
        background: #BDBDAD;
        left: 660px;
        top:210px;
}
#arm{
        position: absolute;
        width: 50px;
        height: 100px;
        background: #EBEB42;
        border-radius: 20px;
        left: 640px;
        transition: transform 1s ease;
}

.rotate{
        transform: rotate(180deg);
}

table{
        position:relative;
        float:left;
        left: 213px;
        top: 80px;
        background: white;
        border: 5px solid #5F7DC4;
        border-radius: 10px;
        width: 350px;
}
input {
        position: relative;
        top:275px;
        left:-100px;
        width: 100px;
        height: 50px;
        padding-right: 50px;
        font-family: 'Luckiest Guy', cursive;
        font-size: 35px;
        color: #F5DA1C;
        text-shadow: #5F7DC4 3px 3px 0, #5F7DC4 0px 0px 0, 
                 #5F7DC4 0px 0px 0, #5F7DC4 3px -3px 0;
}

<!doctype html>
<html>

<head>
        <meta charset="utf-8">
        <title>Pokemon slot machine</title>
        <link href="https://fonts.googleapis.com/css?family=Luckiest+Guy" rel="stylesheet">
  <title>Dice Game</title>  
  <link href="slot3styles.css" rel="stylesheet"> 
  <script src="slot3.js" defer></script>
</head>

<body>
        <h1>POKEMON SLOT MACHINE</h1>
        
  <form name=slots onsubmit="rollem(); return false;">
    <div id="roundsquare"></div>
    <div id="square"></div>
    <div id="squarebottom"></div>    
    <div id="linearm"></div>
    <div id="slider">
      <div id="linearm2"></div>
      <div id="arm"></div>
    </div>     
         
    <table cellspacing=5 cellpadding=2>
      <tr>
        <td> <img src="picachu.png" name=slot1> </td>
        <td> <img src="picachu.png"  name=slot2> </td>
        <td> <img src="picachu.png"  name=slot3> </td>
      </tr>
    </table>
    <tr>
      <th> 
        <td><input type="text" name="txtCoins" value="0" id="coins" readonly></td>
        <td> <input class="button" type=submit value="PLAY"> </td>
      </th>
    </tr>
  </form>
</body>

</html>