In my direct experience, it's a total crap shoot. I have cartridges that are 40 and more years old that sound wonderful. And I have some others with similar age that are clearly not what they used to be. I would hesitate to name names or to say that one type ages more predictably than another (MM vs MC, for example), because I have no data to point specifically at such a conclusion. The good news is that nearly every one of the vintage MM and MI cartridges I have purchased in the last 5-8 years works fine, with maybe one exception. (Jury is out on that one.) I would not be afraid to purchase another vintage cartridge, if I had good faith it was in NOS or near NOS condition, in terms of actual hours of use.
To what level do phono cartridges age?
I’ve seen a few threads on this subject but I’ve not seen anything definitive. I’ve heard that the internal components of phono cartridges deteriorate over time regardless of their use. Am I “on a clock” with regards to my cartridge? Is it a case of “use it or lose it”. Or, should a high end cartridge last as long as the stylus is in good condition and not overly worn? Btw...I currently have a Linn Kandid installed on a Linn LP12.