How do you tell your Cartridge needs replacing?

I don’t think most folks are equipped to evaluate the condition of a stylus, regardless of the type of microscope they have. (I have a bunch of usb ones, and the vintage Shure stylus scope, which is cool in its own right as a period artifact). Me, I can get a lot of mileage from a good cartridge if I am careful, I inspect the cartridge almost after every side, try to avoid any sort of damage in cleaning (largely dry brushing at this point) and am obviously sensitive to the performance of the thing: if it mistracks, distorts, or is audibly obvious misperforming, you may be beyond the point where it needs to be replaced or ’fixed.’ Are your records damaged? Probably not, but don’t push it. Address the cartridge if there is any question.

I think the biggest fallacy for audiophiles is the gradual reduction in sound quality that you get used to, so a fresh iteration is a revelation. I’ve seen this a few times.

I liken this to a fresh pair of sneakers. (Get what I mean?) Vinyl is not for the faint of heart. You gotta stay on it.

Get a bottle of Stylast and use it before playing a side. It is a lubricant that is claimed to reduce wear and extend stylus life. I use it! Michael Fremer claims that the stylus will outlast the suspension!

https://www.gcaudio.com/tips-tricks/how-long-will-my-stylus-last/

https://www.sound-smith.com/articles/stylus-shape-information

We believe that styli should be checked carefully by microscopic exam by someone who knows what to look for at 1000 hours, as that is the typical maximum life for a properly aligned stylus

OP,

keep a log of how many record sides you play over a month or so and assume each one is 20 min or .33 hours.  

then estimate the accumulated hours on your cartridge based on your record playing habits.  

If it is upwards of 1500 hrs or so have it inspected by a qualified dealer.  

I had a cartridge inspected at 1200 hours and it had a lot of life left according to the dealer.  

You could also get a test record that has increasing modulation levels (loudness) and you could note when you hear the onset of mis-tracking and how severe is that mis-tracking.  Later, you can compare that result to what you hear when you are looking for signs of aging.  The problem with a visual inspection by even a qualified dealer is that such inspection will not reveal when the suspension is going bad.  The rubber ring around the cantilever that damps unwanted vibration can go bad even if the stylus is not played, so it is possible that the cartridge has gone bad long before wear even begins to show.

To me, listening remains the best way to determine wear.