I've got 2 of the King Goanna stretchers that I bought second hand. One of them I noticed afterwards was a bit "wobbly". Where the central leg joins into the main poles down the side, the rivets are getting a bit loose. I rang the Oztent support line, and they spent time talking to me (even after I explained I bought them second hand) and in the end advised me to drill out the rivets and replace with similar size bolts with nyloc nuts. That way they shouldn't come undone, but if they do, I can tighten them up again.
That's pretty damn good service! And the other stretcher is an absolute cracker. Definitely recommend Oztent.