Hispano Suiza Hs-52

The Spanish republicans had a licence agrement with Fokker to build the Fokker D-XXI fighter.
They build only one aeroplane but also a lot of parts. But before they could build more aeroplanes the factory was overrun.
After the war a lot of part were used for the Hispano Suiza Hs-52 trainer.
This aeroplane could be armament with machine guns in the wings and a machine gun a the second place, for observer trainer etc.
Who can help me with details how the machine gun was placed at the observers place?
Thanks
Jan