New or used cartridge


I have have good experiences buying a previously owned cart in the past, but have heard several telling me to buy new..  I wish there was a way, to tell how many hours was on a used cart.  Other than putting the cantilever under a microscope,  I see no way concerning the hours/use/condition of a used cart..  I kinda look at it as buying a used car.  Let someone else take the initial "hit". then buy from them, as they're moving over or up.  I have an excellent Koetsu Urushi Black I'm going to put up for sale.  I love it's sound, but am wanting to move up the ladder so to speak.
Please give me opinions concerning this.
handymann
The MicroRidge and similar advanced LineContact styli must be replaced after 2000 hrs, the Conical and Elliptical stily must be replaced every 200-500hrs. 
Handyman, you mention an Urushi.

If you are considering rising in the Koetsu line, note that Koetsu likes to service their own cartridges by completely rebuilding them. It is said that they will not touch a cartridge which has been serviced by another.

Therefore, your options are limited. You could get someone (like Soundsmith) to inspect the cartridge, but not service it. Then, if necessary, send it to Koetsu for rebuilding at great cost. The result of this would be essentially a new Koetsu with Koetsu sound. Unless Koetsu refused to rebuild it because of tampering by the former owner.

Alternatively, you could get someone like Soundsmith to service it at lower cost. But you might not get Koetsu sound or Koetsu longevity.

I have the KRSP with diamond cantilever and like it a lot. Rebuild price will be very high - hope I can afford it come the day. But after 700 hours the stylus still looks good.
Terry9:  Thanks for the info, but there's nothing wrong with my Urushi Black. Just thought I would move up.                                          Steve
@terry9 
Consider having your Koetsu rebuilt through a Japanese or Asian deputy service. E.g. EIFL (Japan) advertises this for low-2000s on stone platinum model. Otherwise, the USA distributor & dealer will each take a hefty cut, and do nothing to expedite the process. Also, the rebuild cost does not rise for the premium stones, so the long-term cost on say a Coralstone can start to look pretty reasonable. 

I've also heard that Koetsu will not touch a cartridge that's been worked on by any 3rd party. Not sure if that still holds, but it certainly keeps me away from any 3rd part work. Over the years I've seen an awful lot of Koetsu with SoundSmith ruby cantilevers "less than 10 hours", etc, for sale.
@mulveling 
Is EIFL an authorized service facility? Their website does not specify.