To test the camera, if you can process photographic paper, a tray and developer and fixer is all that is needed,( plus a darkroom lamp if needed), use a cut piece of photographic multigrade paper, and expose it as a single sheet at about 10 ASA film speed. Process the paper, which will be a negative, and then scan it into a computer and turn it positive in a graphics program like the Gimp etc. It can then be printed out any size. Stephen.
I have a Zeiss-Ikon Cocarette 519/14 fitted with an 8cm, f/6.3 Nettar Anastigmat lens #1165994 in a Derval shutter.
It does have a serial #P93634. The number is impressed into the metal of the body under the removable film holder. This is where the serial #s of my other Cocarettes is also found. It is very hard to see.
From the bodynumber we can deduct a manufacturing year of 1926 or 1927.
From the research of our ZHS member Simon Worsley, there are 2 Cocarettes known with this negative format, the 206 and the later 519/14 (which sports a leather carrying handle and a wire frame finder (amongst others). This makes your camera a Cocarette 206.
The earlier company being Contessa-Nettel and after the merger Zeiss Ikon, more than 150 different models were advertised for the domestic (German) market between 1926 and 1931 by Zeiss Ikon alone!
For this information I rely on the information Simon has given in the Yahoo ZICG Group. When you are really interested in Zeiss Ikon equipment, that is the place to be!