Text box has disappeared from item (using JavaScript)

An issue has arisen in a number of my surveys that use QRT Engine to capture response times (they’re old surveys but I’m midway through a study so I can’t change the design). The issue is that the text box in the image below does not load for this item of the survey. As a result, participants are unable to enter a rating. The javascript for this item is pasted below the image.

Thanks in advance

!



QRTE.Stimulus ({
id: 'Ind_Confidence', //Should be a unique ID, per stimulus in a trial block
onShowFn: function() {
$('Plug').style.display = 'None';

var id = 'confidenceText';
field = document.getElementById(id);

field.style.display = 'inline';
field.focus();
field.select();

function check(rating) {
if (rating && rating >= 0 && rating <= 100) {
return true
} else {
alert ('Please type a number between 0 and 100.')
return false
}
}

// Proceed on 'Enter' key press
field.onkeyup = function(e){
if(e.keyCode == 13 || e.keyCode == 13){
var rating = field.value;
if (check(rating)) {
e.preventDefault();
QRTE.proceed();
return (false)
}
}
}
},

// Save individual confidence rating at end.
onHideFn: function(ele, ts) {
var rating = field.value;
QRTE.setTrialData(ele.userId + '[resp]', rating);
}
});