[Mickebutcher]

I just did this job on my Giulia Super. First of all, I got new rivets from Classic Alfa, but realized I didn't have the correct or suitable pressing tool to press them in place. Very limited availability..
Instead, I modified the rivets by drilling a 2.5mm hole, grinded the top of the rivet down slightly, and then used a 3mm Torx screw to lock the rivet in position. Works great. Finally, I attached my old, slightly tired spring, by using a loop of steel wire to pull it into place. No issues whatsoever in getting it in place. Opens and closes as designed with a good fitting.

 

[Mickebutcher]

The spring really shouldn’t be an issue. As I said, easy to install after the door is in place with rivets and all. Attach spring to body, pull to flap using a wire loop. It sounds like you have a too heavy duty spring for this purpose..? A small, as the original, spring is good enough