Zenith 80. Please help.

[Idie]

Hi everybody! I am new to this forum and have a question about the Zenith 80 medium film camera.
I just bought one of these with three film backs and looking in very good condition. Was promised that it works. Yet, it turns out that I am not able to cock the shutter, which implies that also no film would be wound and the shutter curtain won't move. I am aware that one should not change the exposure speed settings with an uncocked shutter, and I didn't touch it at all when trying the camera out without film. I am also aware that the shutter would not fire with the dark slide in, so I removed it. But whatever I do, the two windows at the camera and the film back stay "red", which makes me believe that the shutter cocking mechanism might not be working as promised. Or I am doing something stupid and just plain wrong - like a little button to press, or having film in the film back ... it is the first time I am trying to play with a Zenith 80 and the manual is rather "brief", so it would not surprise me if I would just be missing a little something.
Is there anyone out there who might be able to help?
Thanks so much!