1994 Volvo 960
I just opened my sunroof after not using it for about a year. I used the toggle switch on the dashboard. It stopped when the vent opened (about a one-inch vertical opening). It won't move either way now. When I push the toggle button to open I hear a "thwack" sound near the motor. I removed the motor cover, and there's a sealed unit behind the headliner, so there's no way to inspect anything without cutting out the headliner.

I wonder if there is a way to close the sunroof manually. I see what looks like a round, button-shaped piece exposed in a cutaway area of the headliner. Could this have to do with how one might crank the sunroof closed?