This is a fix for the navigation buttons.
I found the Next button worked fine but the previous button was trying to navigate to an invalid number in the array when you changed between forwards and backwards navigation.
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In catalog/product_info.php
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// ** REPLACE the entire slideFader function with:
function slideFader(direction){

if (direction == 1) {
if (backSlide==1){
slideStation=slideStation+2
}
alert(slideStation)
if(slideStation == slideList.length){
slideStation = -1;
slideImage = headImage;
slideImageOriginal = "";
}else{
slideImage = slideList[slideStation];
slideImageOriginal = slideListOriginal[slideStation];
}
slideStation++;
backSlide=0;
forwardSlide=1;
}

if (direction == -1) {
if (forwardSlide==1){
slideStation=slideStation-2
}
alert(slideStation)
if (slideStation==-2) {
slideStation= slideList.length-1;
slideImage = slideList[slideStation];
slideImageOriginal = slideListOriginal[slideStation];
}else if (slideStation==-1) {
slideStation= slideList.length;
slideImage = headImage;
slideImageOriginal = "";
}else{
slideImage = slideList[slideStation];
slideImageOriginal = slideListOriginal[slideStation];
}
slideStation--;
backSlide=1;
forwardSlide=0;
}

sPanel = document.getElementById("slidePanel");
sPanel.innerHTML = "";

}


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