While replacing ribbons inside a 1951 Kiev II I found that the rangefinder prism is of German manufacture. S/N of the camera is 517061. A late 1951 camera. Also it seems there's a signature inside. I already found a signature inside another 1951 Kiev II. Best,
The signature looks familiar to me. I don't know when the stock of German parts exactly dried up. The earliest known parts they produced might look indistinguishable.
The most important alteration (beside the use of another ribbon) is the use of (probably) thin beeswax based lubricants that only need slight cleaning. Using oil will get you into trouble, unless you really take apart everything (including the winding gear train) for cleaning and relubrication.
Beware of the Kiev 88 ribbon that is being sold as for use on the Kiev 4 and the Contax. It is a lot thicker.
The four white dots on the rangefinder prism tells it's German part.
I still use Aki Asahi ribbons. As you already know they don't match originals ribbons. A Japanese repairman is currenty selling another ribbons. I've ordered some, will try later.
See how that Russian repairman cleans Kiev shutters, I do the same :
Used to clean it that way, but now I take apart the gear and winding gear train by removing the locking pin from the sprocket shaft. Takes some extra work but the result is promising.
The polyester double sided satin ribbon from Berisfords can be used as a substitute for the Arsenal ribbon. Which works fine but is not durable. The Aki Asahi ribbon works fine in very early Kiev's and Contax camera's.
I had quite a discussion about using the Arsenal ribbons in later Kiev cameras by 'pinching the slots' with someone. Never ever do this. It is an irriversable modification that can hardly be undone. The resistance and friction on this point is very critical.