My spring has sprung...

It's a mighty strong spring. The hinge travel isn't any greater at the workbench.
I don't know if they are all the same or what model you have. My hinge springs have push nut like keepers much like those that hold the hinge on the car. I can't see one good cause for the keeper to leave or spring to jump off unless the hinge is worn.
I'll go take a picture real quick. I should have started with that I'm sorry. It was early and I hadn't had my first cup of coffee!