Monitor tilts down

Is there a bolt to tighten down in the back?

It's not a great solution, but I just stuck a really small cardboard box between the stand and the monitor. I think there's some sort of spring inside that breaks/comes loose. I took off the monitor (for another repair, this time the power supply, blech...) but can't see a way to investigate the mecanism inside the stand. Sorry I can't be more helpful.