Turn the grey ring around the lens (where the light comes from) until the image is sharp.

Hi, I've worked on quite a few NEC VT595s & found there is a problem with very small screws coming loose below the zoom adjustment ring. The only way to fix it is to dismantle the unit & replace the screws or to replace the zoom/focus part off a parts projector.
I did notice that if I move the lens up & down by hand I can feel it's loose & can get it to focus by holding the lens so it moves upwards & then adjust the focus. Doesn't always work but play with it & see, it's a lot cheaper than replacing the part.