I have an old DK Jr cab, and sometimes (most times) when I turn it on, the monitor is a mess of diagonal lines. The game is working fine, as you can play it blind. I have pretty bad power outlets I suspect. Is it possible this is a lack of proper power, or is the monitor dying on me?
I don't think power would do that. It could be a couple simple things, a maladjusted horizontal hold (does it have one?), or maybe i disconnected sync wire.