The hood has either one or two torsion springs at the shaft on each flap. Assuming it's not bent they should pop up freely. The ears will pop off the shaft if they're spread slightly not bent.
On the hood I own, the top panel (the one that closes the whole thing) does not pop up at all. I'd like to access the spring(s) to see what happens there, but have no clue about a way to remove the different part to fix this issue.
I found the beginning of the dismantling way : the hood's top is held in place by a pin which is pushed by a spring... now I have the hood in two pieces, and can see that the issue is that the spring that lifts the top is not correctly seated... I'll try to post some images later. !
As said earlier, I finally found my way through it.
The top of the hood is attached by two rods (similarly to some wrist watch bands attachment).
I was able to set the top free, then I lubricated the spring and the rods, and reinserted everything in place.
Of course, I had to do it again since the torsion spring was not loaded enough to get the hood to 'pop' and keep wide open. To reassemble everything and charge the spring, I used a toothwpick to keep the sides and rear of the WLF closed, and hold the spring tensioned until I could release it after reassembly.
It also helped to unlock the loupe, so that it did not get in the way.