@andychris If you will search audiogon you will find my detailed explanation how do they work with broken cartridges if you purchased them from authorized dealer (it's easy to check by serial number).
1) They can ONLY give you a NEW cartridge and you will pay at least 60% of 100% retail price. You can also upgrade to the next model. At least in the USA it workd like that and you can still contact Mehran at sorasound The cartridge must be an original, it means you can not send them back a ZYX cartridge if somebody else tried to fix it.
2) ZYX cartridge body is sealed, the original cantilever is way different from any other cantilevers on the market, check
this picture of my ex Airy3. If you want to experiment with your broken cartridge you can send it to some other re-tippers, but it depends what you're gonna do (just replace the diamond or replace the whole cantilever).
3) If you want to replace the cantilever someone will have to crack the cartridge body. Then you will get a cartridge which is no longer ZYX cartridge.
4) The process via Nakatsuka-San is the best if you're ok with the price, you will get a brand new cartridge with new serial number. But i think you can source brand new cartridge somewhere else for lower price (maybe used or demo).