76 Duster SUNROOF QUESTIONS

I picked up a 76 Duster with the crank back sunroof.........

I've NEVER had one of these before.........The seller had the half-vinyl roof professionally recovered, and a new headliner installed at the same time......According to the seller, the installer said that the "chains" inside the mechanism of the sunroof looked like they could break if you used it too much..........the seller put it in a way that scared me a bit, and now I'm wanting to open the thing but can't get myself to crank it for fear of a disaster.

Can you guys lend any advice, service tips, tricks, ANYTHING that can give me some insight into these mechanisms and what I can do? Can it be easily serviced? (I assume not).............Any advice on opening or closing it? There's no glass by the way, just vinyl on the outside and headliner material inside.

THANKS.............:dontknow::dontknow: