One thing I would advise for folks considering a retip on Koetsu: Koetsu used an "interface" type mount, where the stylus is fitted through a collar of different (softer) metal, then into a groove prepared in the boron. Glue is added mostly on the other side, opposite the collar. It’s generally a very clean looking mount under magnification, with less glue used.
I believe there’s a Japanese supplier of the whole boron rod cantilever & stylus with this interface mount (Ogura?), which should be very similar to what Koetsu used. Personally, this would be my preference. The old cantilever can be removed from joint pipe, and the new one can be added in - stylus mount and all.
When you compare to Euro and USA style tip mounts, they use a lot of visible glue - it either looks like a mound of cement (Benz, Van den Hul) or a clear-ish bubble (Ortofon).
The interface mount will track closely to what was originally intended by Koetsu. It’s totally the owner’s perogative to try something different (and I do quite like Fritz Gygers), but it’s something to keep in mind if you want to keep your Koetsu as close to original as possible.
Ana Mighty Sound in France has shown retip work that tracks beautifully with that of an original Koetsu tip. Same with suakimlp.com, in Vietnam. And I believe Joeseph Long (groovetickler) is also easily capabale of this (or anything else you might want). Those are the 3 I’d trust for keeping a Koetsu as close as possible to original performance.
