You can see the original nut up in http://cimg0.ibsrv.net/gimg/www.6speedonline.com-vbulletin/220x165-1/80-a_convertible_latch_88b892ad8d741567c5b71a19bd2c0392e124f50d.jpgthere. It has split on both sides and in several vertical places. it looks like it was designed to fail!
