The Yashica's are fairly robust cameras if you don't beat them up. I bought a Yashica D from a wedding photographer 34 years ago. He had used it since new as a daily shooter. It has never been serviced and still has accurate shutter speeds and winding with no overlap. It seems that the most important thing is to use it or at least exercise the shutter on a regular basis. Cameras that just sit around or have been stored for long periods tend to have problems with the slow speeds most of the time.