This happened to me....last march...I know exactly the screw you are talking about....I wounded the little screwdriver hole thing up to a point..as I was leveling it so the beam aimed downwards and then the screw in the back popped out and the aim of the projector shot upwards....
What I did was (after several troubleshoots) replace the rear screw but don't screw it in tight...and rewind the screwdriver hole thing on top to lower the light (apparantly the default aim setting on my ZKW projection, or zero position, is aimed up). Turn it really slowly....I mean slow, not medium speed. And after awhile it will adjust to the aim you want.....This should work.
Mine are aimed to the lowest.....
good luck...