Help with hi-hat stand

[Composer of Requiems]

Okay, so I have this ludwig hi-hat stand. The problem with it is that after staring at it for ages, I still can't work out how to adjust the spring tension. I suspect I can't. But I think I'll ask around here anyway, just in case... how do I loosen or tighten the spring tension on this model?

This is what it looks like:

I was thinking of opening it up and looking for the spring inside, but I'm not sure if I want to risk it, since I have no idea what the inside looks like. It doesn't seem to be screwed and removable, but bolted and fastened...

Does anyone have any suggestions?