As I’ve said so may times before, finding a piano technician with the skills to both diagnose and execute this work at a high level is rare. If you find one, hold onto her ferociously. Refer her to other people who will treat her with the respect and honor she deserves.
It comes down to this: high-end piano work, acquiring and perfecting the skills to make a piano sing, is hard. It takes a tremendous amount of energy and focus. Only a relatively small percentage of piano techs will make the sacrifice to actually get there.
When you find one that does—and you just have to look sensibly—hold onto them, my friends.