I really only know basic electronics, and not much at that... so I'm
not sure that I know what I'm looking for. I've looked the main board
over (p/n DUNTK9254WE) and aside from some darkened spots underneath
large 1/2W (?) resistors, nothing looks out of the ordinary. As for the
flyback transformer, nothing appears amiss about it either... but once
again, I don't totally know what I'm looking for.

Regarding the arcing... I assume I need to have the set powered on with
the case opened to do that. How should I do that - i.e. is it okay to
have the set laying on it's face, or does it need to be upright like it
would be normally, etc?

Thanks for the help!
Baral'heia