Warning signs you have a worn out cartridge

It suddenly sounds great before it fails.

Send it to a retipper for inspection.

You'll hear noticeable distortion on your go-to pressings. 

I have a Kiseki Blue boxed up waiting for a re-tip. 

Here's an article I wrote on the topic:

https://www.thebrokenrecord.net/the-fascinating-lifecycle-of-our-stereo-cartridge/

@tablejockey very good suggestion.  VAS is probably the one to recommend as SoundSmith seems quite backed up lately perhaps due to their recent relocation.  @thebrokenrecord that is a nice article you wrote.  Thanks for sharing it.  OP, If you can find a way to inspect your stylus, I recommend a twice yearly inspection under a microscope.  Insert the stylus under the lens facing up so you are looking down at the tip.  A worn stylus will show two shiny facets, one on each side of the tip.  If the stylus is wearing unevenly these two facets will not be the same size.  Depending on the quality of the microscope the depth of field may require you to move from the tip down the sides of the stylus to get a complete picture.  Digital microscopes can be purchased for not a lot of money.  Of course wear of the stylus is only the main issue so listen for sound degradation.  Some will tell you that as the stylus wears it can damage the vinyl, that may be so for a conical stylus, which starts life with smooth walls, but as it wears it will develop sharp edges.  For Shibata and fine line, however, they wear smooth so are much less likely to damage your records before sound deterioration for other reasons such as cantilever sag occur.  Again, your ears are your best early warning device.