I'm really fortunate. I can do some of the jobs myself, which is a skill I developed very early in life. I've always been poor so I had to be able to fix things because I couldn't afford the repair guy.
If the job is difficult, I go to an authorized repair guy in Westminster, Maryland who can fix anything electronic. And, there have been times when he told me to go down the street and have a burger for lunch and he would have the keyboard ready when I returned. He never disappointed me. To top it off, his rates are half what most other repair centers are.
The only time I needed his services for a Yamaha keyboard was when my backup PSR-3000's midi out board had a chip fail. Instead of replacing the entire board, which some folks tend to do, he merely tested the board, figured out where the offending part was, and quickly replaced it.
Cheers,
Gary