I had heard about this display issue, as well. And I also heard the theory that the issue was not in the actual display, but instead in a circuit that feeds the power to the display -- which would be why replacing only the display did not solve the issue. But I also read that if a particular model has the defect, then it is there right out of the box, and not something that happens down the road -- but that could have been wrong.
I hope Yamaha really did take care of this, because otherwise, the E473 is a pretty impressive keyboard for the price.