Thank you for your kind replies!
Here is the link to a short video, showing her run on compressed air (please excuse the unprofessional camera movements, but I wanted to shoot the vid before I go on dismantling the engine as the base needs to be fixed, and with only two hands...)
Runs a bit out of round, especially when you change direction - but it runs.
Maybe it is much better with steam and after fixing. Arnold
I am optimistic, Arnold,
the nozzle of the air-line does not fit the valve opening well, so I can just press the silicon hose I have attached against the (not really plane) surface of the valve. In addition, there are the many screws, bolts and links of the double valve gear - ab it too much for my low pressure compressor...