I know the digital Korteks have the S-correction switches (they're all MOSFETs on the Kortek, IIRC, but one may be a relay on the WG) go out somewhat frequently, which can do this. Obviously a dead cap in the horiz out could do it, too.
What frequency are you running it at?
I don't know as much about the WG, either, but yes, everybody seems to agree that they're a mess. They're famous for taking out half the components on the board when they break.