For alignment, the final mirror in my testing was only useful for getting the beam central through the tip of the cone. Very little further adjustment is possible without causing reflections and off center beam. So when you drill holes in acrylic and find that you have an angle, you have to go back to the laser mounts. I found that a full turn on one of the plastic screws at the high voltage end of the tube (probably only 1mm movement) was enough to change the angle to fix it (after the further necessary resetting of mirror 1 and 2.
I could curse the narrow nozzle, but it greatly improves the efficiency of air assist.