I was in Japan last year and I was in Nakano Broadway which I’m sure you’re familiar with. Perhaps you can give one of the stores a ring for a recommendation as all sorts of watches go through the hands of dealers in there.
I entrust all my watch servicing to アヤセオプト, five minutes from Ayase station. The guy there is a dream, does work for a reasonable price, and has been extremely helpful in sourcing replacement parts. He's a big-time Omega enthusiast and seems to enjoy the challenge of hunting for whatever you need. If you're in Taito-ku, it would seem to be conveniently located. Edit: Oh, sorry, maybe you were referring to アトリエキノコ up there.
Hi 'Atelier Kinoko' is located in Okachimachi, Taito-ku. I have never used 'Atelier Kinoko'. I don't live in the Tokyo/Yokohama area. 'Atelier Kinoko' is a store with a good reputation on forums like reddit in Japan. That's why I introduced it. 'Zenmai Works' is another reputable store on the boards. You can check it out at https://www.zenmaiworks.jp/ By the way, the store I'm using is my local 'Eyeglasses, Jewelry and watch Shibada' and manufacturer https://tokei-shibata.com/ 'Ayase Opt' is probably a store in Higashi Ayase, Adachi-ku, close to Taito-ku. http://www.ayase-opto.com/ Takoyaki is very delicious! Sorry for the strange English since using a translation service
Ayase Opt is near Ayase Station on the Chiyoda line. https://goo.gl/maps/zHS5uoRGTjugpx8s9 This is the guy: https://www.nytimes.com/2018/03/23/style/watches-repairs-tokyo.html?searchResultPosition=10