A few days ago I bought a 5x7 technical camera with a Schneider-Kreuznach Symmar 1:5,6/300 1:12/500 lens. The lens is mounted in a Compound 3 shutter. The shutter worked but had only one speed at all selected speeds. I took it apart and repaired it. Now it works fine. There is something I want to share with other photographers who use a Compound shutter. After cocking the shutter needs at least three seconds to get its starting position. This is only visible inside the shutter. The delay of your shutter is easy detectable. It takes two tests. Set the time to one second. After cocking count to ten before pressing the shutter. The second time press the shutter immediately after cocking. You can hear the difference. My advice: take at least ten seconds after cocking before you fire a Compound shutter.