countdown message appears with !remaining but the number doesn't count down

It looks like the IDs are screwed up. E.g. the id for the textarea is edit-field-filerequirements-0-value-1 whereas Drupal.settings.maxlength has edit-field-filerequirements-0-value -- so the actual ID has an extra "-1" appended to it, although I don't understand why.

So if I hack the code in maxlength.js around line 30:
var element = $("#"+ id+'-1');

Then at least the correct element is set with the keyup event. But when Drupal.maxLength_limit is called, the field doesn't have an attribute "limit". What should this look like?

And finally, even if I hack the code to set the limit manually, the following line still doesn't update the HTML:
$('#maxlength-'+field.attr('id').substr(5) + ' span.maxlength-counter-remaining').html(remainingCnt.toString());

Can anyone tell me what's going on inside maxlength.js ?