The lens cells would have to be removed to access the shutter for servicing, so it is possible they were put in wrong. If you're that concerned about it, I'd ship it off to someone in the US or the EU to have it properly serviced (even with the shipping cost, it will be worth doing, as the camera seems to otherwise be functioning). I have a 2.8E that I bought in well-worn condition that needed a major overhaul. The servicing cost me almost $400 USD, but now I have a camera that will last me another 20 years. When you spread that cost out over the life of the camera, it comes down to pennies a day. Very economical.