I think I understand why the old one worked and not the new one. The old one used a variable to point to the scripts’ location.
<script src="<?php echo $ssgDir; ?>scripts/language.min.js"></script>
<script src="<?php echo $ssgDir; ?>scripts/gauges.js"></script>
The new version has the location hard coded.
<script src="scripts/language.min.js"></script>
<script src="scripts/gauges.js"></script>
Tom