The alignment of the image on the screen is not quite trivial, because the central screw to adjust the friction of the base plate is accessible only before mounting the projector and must be previously adjusted in strength accordingly. Real Fummelkram if you have missed it, because then you have to dismantle the projector again and tighten the screw again or loosen, possibly even several times :-(.
Another tip: The Sicherungsschraubem for the pipe will not be dismantled, but squeezed like an umbrella or tent poles, clicked from the inside in the holes provided, and then backed up. Only those who want to be absolutely sure the screws turns out beforehand and then turns them from outside again firmly (clockwise).