This elbow piece is leaking from the flexible joint. Looks fairly straightforward to swap - hopefully one bolt. But I cannot get close to finding a spare, not knowing what's it called! Camping at half term . . .
i dont think they make these anymore, just to prone to leaks and dangerous - especially on boats. If you want to keep the cooker i'm sure you can find a fixed fitting on ebay and tighten it in the position to suit your set up.