Just wanted to share this info. I first ran into this problem with a Pentacon 6 years ago, then today ran into it with the first roll of film I ran through a Zenit-1 I fixed some film transport issues with. Obviously this shutter problem could be repaired, but the work around is simple enough I don't bother if the shutter otherwise works OK.
The problem is: there is a tiny gap between the shutter curtains when you wind the camera. On a lever wind camera it makes these weird streaks that look like the shutter is banding. On a knob wind camera, you end up with random vertical lines on the negative, in the places you pause the gap as you wind the knob. On this Zenit, they are on every negative but in different places.
The work around? Simply cover the lens when you are winding the camera. Here is an example of what this looks like in case you even run into this, and another shot with the same camera taken later just covering the lens with my hand while winding. Never seen this except on old soviet cameras but it's not a deal breaker if you know this is the problem and cover the lens when winding.