I can't be sure, but it's highly likely a shutter problem.
Before I could start on my test roll, I found that my camera's slower shutter speeds were no longer as slow as they could be. I sent the body back to where I bough it, and they're going to send me a replacement.
I'm hoping the two problems are related.
It certainly is a possibility. I hope you get good, and quick, and satisfactory resolution. When all is resolved, I feel certain you will find that the Kiev 88 represents a lot of bang for the buck. I enjoy using mine, which I call my "Hasselbladski."