That dead pixel pollicy comes from a few years back...
overhere in Holland someone took it to court for a computer screen and he won the case, current production technologies are at such a high level that selling screens with bad/dead pixels should not be allowed.
The customer allways has the right to buy a flawless opperating device... If Yamaha does not replace your screen with a flawless working one, (espescially with the current pricing and the screen production cost being lower then $100) people should never again from them, as they clearly don't care for the customers in that case.
So call your reseller and demand a new screen for your unit.