If someone's over-oiled the hinges the hinge assembly won't hold the hood up. It doesn't take much lube to ruin everything. Degrease the hinge joints if you think they've been oiled.
If that's not the answer, take a look at whether there's a way to rotate the center pin that the inner end of the coiled hood spring is connected to, to try and put more preload on the hinge springs. I don't think that pin is
made to easily be rotated of course, it might be spot welded or something, but if it
can be rotated one way or the other it'll put more tension on the spring.
Somebody put it all together in the 'hood spring factory' right? So it is an assembly that might be able to be 'adjusted'.
I took a long look at mine a few years ago trying to see how it all went together etc. but the details are fuzzy at the moment. Give it all a good look down where the spring is..