The new-to-me Agfa Ventura survived my unlocking of the lens front element, and there is a good indication that I am back with infinity focus. That was work, I feel like I passed the membership test in a special club
Here is a puzzling item though.
Apparently, it is not quite like the simpler Isolette I, but not as feature-rich as the isolette II.
There are multiple sources for manuals for both, but nothing I found on the Ventura itself.
So, I have a hard time figuring what a slider button, located to the right of the shutter release button, does.
No Isolette documentation that I see have it. I suspect it has to do with film advance/shutter lock, protecting or un-jamming it, but a confirmation would be nice.