I thought I'd start a thread for this...
On a dead screen unit I have, I connected the TV Tuner and a BAD picture (looked like a film negative) with static etc actually showed up. I then turned off the tuner and the game screen came on. Again though, it was 'streaky' and looked like it had a slow refresh rate (non tech terms I know) as everything was blurring pretty badly. It seems like the tv tuner signal actually 'jump started' the screen and now it will work (terrible picture though) every time I fire it up.
I then took another screen (basically the entire 'top half' of a TE) and plugged it into the dead screen unit and it jumped to life.
So, it looks like the screen issues are in the screen as opposed to being a capacitor issue etc...Not sure where to go from here with it but thought I'd put this info out there if others have also been tinkering to find a solution to this issue.