How do you know when to replace the stylist?

I second what audioquest 4life says. I am in the process of replacing my current cartridge. I started loosing detail in the high frequencies and certain passages started sounding more sibilant, and some music would just totally distort to where I couldn't listen. Basically the cartridge couldn't track well any more. It sounded like bad inner groove distortion.

At one time: Every serious audio salon(not going back to the "stylist" thing- honest) had a microscope which which to inspect your stylus. I'm certain(if you live near a metropolitan area) you could still find one. Really- any decent microscope would do. Just look for wear at the points of contact with the groove walls. Here are a couple stylus retipper tips:(http://www.vandenhul.com/Default.aspx?page=p&id=29) (http://www.sound-smith.com/retip/) If you have a cartridge that's honestly worth the effort Van den Hul is the bomb!! Plug, "stylus retipping" in your searchbar for more options.

OH- On the Van den Hul site: You have to click on "phono cartridges"(left of page), then "extra services" at the bottom of the cartridge list.