The more time is passing by, the more Contax II owners and users will have to learn how to repair their cameras themselves, for no pro repairer will want to tackle that camera - not that it's particularly complicated (although it is in some ways), but just because of the time consuming.
Overhauling that camera and installing new shutter ribbons (and, most of the time, a new lower curtain drum roller main spring) can take more than 40 hours of work if it's done properly and with the amount of care the camera deserves. No professional repairer can afford to do this at cost.
Plus, you'll probably have to re-cement the RF wedge prism, to clean and relube the focusing helix, to re-do the light seals of the whole top cover casting, to clean the VF optics inside and out, etc.
The DIY thing is possible - think of our RFF fellow Kevcaster out there who started from scratch and promptly began very handy at servicing those cameras. 😉
Oleg more than probably installed a Kiev shutter unit in your Contax II but for a user it's probably the best solution. Not only did you get fresh shutter ribbons but a less tired lower curtain drum roller main spring, and the like. Broken shutter ribbons aren't the only illness of the original Zeiss shutter if this one has got an high mileage.