I posted a requested for help a few weeks ago to fix my Kohno 30 tuners, which have a 39 mm spacing, and I could not find parts or new tuners. The tuners were slipping so badly that they would not stay in tune during a piece. There were several helpful suggestions, including two sources for Gotoh and one suggestion to contact Sakurai/Kohno. There were also other sources, such as Germany. This is a report on what I did.
I bought a set of $17 Gotohs and switched out the crown gears, which were worn on the old set. The new gears were a little different, especially with a sharper angle on the gooves, but hey fit and partly improved the workings-but not enough. So, I bought a set of Gotoh from Allparts for $82 including shipping. They looked a little different than the originals, so I then bought a set of Gotoh from Sakurai for $100 including shipping. The $17 set is a differnt mechanical design, which I will not discuss further. The Allparts and Sakurai supplied sets were identical to each other, except that the metal posts inside the plastic rollers were a different color. The new sets differed from the original set in that the keys on the old were oval, and the new are rectangular. The new ones also have steeper crown gears than the old, but the worm gears look the same as the old. The old set had the tuning posts riveted over on the end opposite the keys, while the Allparts and Skurai provided sets are assembled with hex nuts. Also, the Allparts and Sakurai sets plates are stamped with a very slightly different die than the original, which I assume is just a factory replacement of an old, worn die. The old set, cheap set, and Sakurai set are all 14:1. I did not open the Allparts set yet, but I assume that they will also be 14:1, although the advertisement says 15:1. The workings of the new set are tight. The original set was loose from day one when not under string tension. I think that was the way they were designed, because a rather renown luthier commented to me 20 years ago that it was interesting that Kohno used keys that were loose when not under tension, but worked fine when strung up. So, I put in the Sakurai provide set and the guitar seems fine.
As a bit of an epilogue, I had never lubricated the keys in 25 years. Jose Ramirez III's article/book comments that failure to lubricate tuning keys will eventually result in keys that will never stay in tune. So, now I will be lubricating the gears every time I change strings.
Thanks again for the help.
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