To follow on my previous post. I had my Dynavector XV-1s factory rebuilt early last year. It came back better than it ever was before. The distributor (he’s local to me and told me himself) said when they rebuilt it they included improvements to the design they had made since mine was new. Only the body and magnets remained from the original. I essentially got an improved version of my original that’s like new, and it sounds better than I ever remember the original.
OTOH: I had someone tell me a 3rd party retip they got back was a butcher job. The re-tip servicer cut off the cantilever and slipped another one over the remaining shaft with a new tip, but it changed the sound and performance for the worse.
I suppose you get what you pay for. Do the research if the cartridge has value. I have two Lyra Atlas and a DV XV-1s. I plan to stand pat with official factory rebuilds for them all. It’s costly but factory service preserves the cartridges as they are meant to be.