Thanks guys
Investing it, I put a couple of layers of rattle tape in place of the plastic bit (5). When I closed the top it sat up at the front end. When opened, the tape had a cut in it. Long story short, the grey plastic bit on the poptop hooks under the metal stay (the part 5 stops rattles as it's on the edge that goes past the grey bit). The reason the poptop was sitting up, is the broken clip was wedged under the roof hinge. The grey hook part on the roof was too far forward, it looks like it hit part 5 and broke it. The clunk on opening was when it came past the stay. I have moved the grey hook back around 1mm and all seems ok.