I've just received my first WA lens. Directly from KEH, a mint looking Super Angulon 90mm mounted in a syncro compur shutter. Everything looks just wonderful and almost new but I don't understand how it's supposed to stay opened for composing and focusing. There is a small lever on the shutter's side, but there is no way to leave it opened. Is something missing? Do I need some additional accessory or it's supposed to be like that?