Black lines on my screen

I bought this Powerbook with a couple of issues. One was not charging so I swapped out the DC board and solved that. The other was dark lines across the bottom third of the screen. When even light pressure is applied to the edge of the screen the lines disappear.

I thought this was an lcd problem so I swapped in a working one and I still have the same lines. I cannot think what the light pressure at the side on the screen does and the PB works fine with a clothes peg on the side of the screen, but the perfectionist in me would like it to work without the peg.

Any ideas out there?