A small bracket (shown in red) near either side of the clutch cover is free to rotate about the display hinge and must be inserted behind the heat sink framework for the display to seat properly.
Before completely lowering the display onto the lower case, use a spudger to rotate the bracket toward the rear edge of your PowerBook, and insert the bracket between the heat sink framework and the adjacent spring. The second picture shows the bracket correctly installed.
When removing the display screws, keep track of the thin metal bracket (shown in green) under the screws on the inner display bracket.
The outer display bracket (shown in orange) simply slides onto the spiral display spring. Be sure to press it on before installing your display into the lower case.