Fixing sentimental switchblade

Hey guys! I have an old switchblade from my grandfather who passed away almost 10 years ago.

Unfortunately, it no longer automatically opens when I press the button – it just unlocks the mechanism so I can manually open it up.

I’d love to find a way to restore the automatic opening, maybe if its a broken spring or something?

Any advice would be appreciated! I added a few photos incase anyone recognises the make or model.

by Icy_Stranger9934