No doubt Yamaha including Masaki Sakurai use Gotoh tuners thesedays. But in the past Kohno used Rodgers tuners and Yamaha used Karl Hofner tuner for the Yamaha GC30a guitars which are equivalent with the GC70s. For the GC71 model, Yamaha didn't inform the brand of tuning machine mounted on the guitar.
The GC 71 is a derivative of Hauser 1 and Santos Hernandez. The headshape has three lobes the same with Hauser. And Hauser installed Landstorfer (subsequently Reischl). So my GC 71 has a tuning machine similar to Landstorfer with three lobe headshape.
My Oskar Graf has a Reischl tuning machine. When I compare the two, the tuning machine of GC71 resembles Reischl except its side plate has an engraved motive. The worm, gear, sleeve, MOP button shape is identical with Reischl. So I would assume Yamaha in 1984 used Reischl for the GC 71.
The purpose for me to inquire is that I plan to replace the existing tuning machine with a Reischl which is now not available in the market. Reischl retired a few years back. I asked Fritz Ober to locate a Reischl tuning machine for me.
It may be good to ask Akio Naniki directly, but I just don't know where to contact Mr. Naniki.
Masaru Kohno No.50 - 1981
Yamaha GC 71 - 1984
Gary Southwell - 1997 ex. Julian Bream - a bench copy of 'Hauser 1940'
Oskar Graf - 2000
Fritz Ober 'Hauser 1' - 2007
Richard Brune 'Fleta 1956' - 2011
Andrea Tacchi 'Bouchet' - 2014