Beware of NOS (New Old Stock) MMC cartridges.
The diamond tips are in top shape, as they should be - never having been used, but what you can't see is the internal rubber mounting. That internal rubber mounting is THE weak link in the entire B&O cartridge technology.
After 15+ years, the odds are better than even that the rubber decay is well advanced, and after a few months, your "new" cartridge will be good for only the trashcan.
I highly doubt that any retipping service is viable on a B&O cartridge - no retipping service is going to be able to get at the insides of a sealed B&O cartridge to service the rubber mounting.
Retipping is just that - replacing the stylus - and if you CAN see an existing diamond stylus on your B&O cartridge, well then, it don't need no retipping!!!
Having said that, Soundsmith does offer a REBUILDING service for MMC2's and MMC1's at a lower price than a new cartridge, so if you have either of the top models, then that would probably be the way to go.
Menahem