who knows ZYX retipping or refurbish ?

Send it to AJ VanDenHul in Amsterdam. The WORLD'S BEST mc cartridge expert!

I don't think anyone can tell you what the cartridge needs without carefully inspecting it first.

Sorry I didn't explained very well. If I send it back to ZYX for repair, what do they do ? :       retipp ? exchange ? repair ?   some say they refurbich, some say they send you a new one. What is the truth ?

''Refurbishing'' by the manufacturer means removing the existing
 generator and putting a brand new generator instead. You get   a new cartridge in the existing body. ''Refurbishing'' by an retiper
may include cleaning the cart from small black particles, new suspension and new stylus or cantilever/stylus combo. ZYX has
unusual stylus mounting so stylus only retip is not probable.
This means , say, new boron cantilever + chosen stylus shape
but the price is + 500 euro. Cleaning and new suspension means
added costs. My advice: write to ''Expert stylus'' in UK and post
your cart to them after appointment. They will inspect your cart and inform you about their possibilities. You can then decide what you want to do.

andychris If I send it back to ZYX for repair, what do they do ?

No one can answer this question - including Zyx - until they examine the cartridge. In the case of Zyx, they offer no service at all when a cartridge has not been purchased through proper channels, so I would imagine that would be the first thing they would ascertain before conducting a thorough inspection.