Yamaha has repaired many, many out of warranty keyboards at no charge. The S900 immediately comes to mind with its failing display.
The best in-warranty folks you'll ever run across is Logitech. When a single speaker fails they send you an brand-new, replacement sound system. No charge for shipping, no returns necessary, just a complete system replacement.
Gary

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PSR-S950, TC Helicon Harmony-M, Digitech VR, Samson Q7, Sennheiser E855, Custom Console, and lots of other silly stuff!
K+E=W (Knowledge Plus Experience = Wisdom.)