Camera aperture defective?

Good evening, I found an Agfa Silette Vario (Agfa color-agnar 1:3.5/45). I think the aperture is defective, because when I turn three different dials for setting focus, exposure time, and another dial, nothing happens. Shouldn't the aperture normally open or close further? During exposure, it makes a grinding noise. When I load a film, push…