Yamaha has always been good at having people who'll talk to you on the phone.

Yamaha Tech Help: I've gotten help from this number for more than twenty years:
714 522-9105.

This number is/was the number of a trainer: 714 522-9088

If all else fails, you could try the private service company that's almost directly across the street from Yamaha:
(714) 562-7400
[email protected]

Yamaha Parts might be able to reach someone who could help:
714 522-9958
7:00-12:00 & 1:00-4:30 PST