Hmm, it seems like you’re quite familiar with Kawai’s “customer-service,” and I wonder, could it be because you were on the phone with them on a daily basis? 😁
“No, Kawai, I called about the wobbly key, guitar-like bass, and one stuck C yesterday; today I’m calling about an incessant hiss, a vibration, a lateral-moving key, two buttons that won’t give, and a’ bench!”
Surely, they’re nice, now that they’ve been on the phone with you on a daily basis, you’re like family; however, since you rarely ever needed to call Yamaha about any issues, they were a bit shy about calling you back at the wrong time, and waking you up; so you see, they were not being rude for/by not calling back, but rather shy & apprehensive.
I love Yamaha “customer-service” because rarely do I need it; now, that’s the mark of a well-built product!