Gives you the sh$ts don't it when the hood drops on your head without warning
My FB is doing the same thing.Some blokes buy helper springs that will fit inside the original springs and stop the problem and I'm about to go down that part myself.I think you would need an assistant to help remove/refit the springs as they have a fair bit of tension on them even when thay have lost some of their original factory tension.
Someone had a pic of the helper spring setup but it was a while ago now.Maybe try typing bonnet springs in the forum search area and it might come up.
I'd be interested to know if there was a new replacement for the original springs.
