I have the same problem unfortunately. It started off as intermittent and got steadily worse. It was 'fixable' by jiggling the display open/closed a bit.
I thought it would be a faulty cable with an intermittent contact - but I replaced the cable and it made no difference.
So I guess you're right - and it needs a new display...
colin
PS. I suppose taking the display unit apart is out of the question?
