Hi there. This sounds like the pronged clutch is not engaging properly - please see my website http://kiev88.atwebpages.com/page3.htm and scroll down to 'Shutter curtains', see the left hand image with the red circle. Now you can actually see this if you remove the lens and very slowly wind the shutter. There is a lever in the winding gear which presses the prongs of the clutch together - you should be able to see it happening. The Salyut camera is a clone of the Hasselblad 1600F and works in exactly the same way. Sadly the mechanism wears with time and this is a classic symptom. The lever in the winding gear has a follower on it which follows a cam under the winding knob - if this wears the clutch is not fully engaged (there is a click latch which snaps into place, and is unfastened when the shutter releases). Any attempt to dismantle will likely end in disaster - I have replaced this very component in my Salyut and it took a huge amount of time to get it back together/working correctly.