Not much ever goes wrong with a cartridge - they will last a very long time so I wouldn't worry about the cartridge body. If the cartridge has a user replaceable stylus, it is the stylus that wears - not the cartridge. Typical life of a MM stylus is around 1000-1200 hours if taken care of and played on good vinyl. And yes you can see the wearing of the diamond using a good loupe or microscope to inspect it. But you will usually hear deterioration in its sound quality first as the tip off. Same lifespan for a non replaceable MC cartridge.
The best way is to know when its nearing its end of life is to simply keep track of hours - round up to an hour an LP, figure how many you listen to in a week and do the math. But you have to start with a brand stylus.
For this reason, I never buy used cartridges. The history of the stylus is often unknown. I agree with you that this is a big gamble.
The best way is to know when its nearing its end of life is to simply keep track of hours - round up to an hour an LP, figure how many you listen to in a week and do the math. But you have to start with a brand stylus.
For this reason, I never buy used cartridges. The history of the stylus is often unknown. I agree with you that this is a big gamble.