Cut a strip of pop can aluminum to fit into the underlug/pivot, curl it in, even use a little super-glue to hold it (a LITTLE), and put it together. That will tighten it up enough to tell you a few things. If it is still loose do another strip. When it locks up tight (and it may take a few 'firm' closings to seat it all in), you can really tell the difference from when you started. You will also have material to mic to see how much of a feeler gauge shim you will ultimately want to make.