I'm working on a Sputnik Camera for a friend. The shutter blades won't close if the aperture is set smaller than around f/22. Whatever is holding it back is beneath the shutter and I can't see it to troubleshoot. Does anyone have ideas on why this might be? Once it sticks, I can release the shutter blades only by gently moving the aperture back to a wider setting. Also, is it bad to adjust the aperture while the shutter is open on bulb? When I do this, I feel something sticking and restricting the aperture movement. Eventually whatever it is 'pops' and the aperture can continue to move. I have another Sputnik and it doesn't have a problem with sticking shutter blades or restriction on the aperture while the blades are open. Thanks!