Depending how M3 is mounted you may be able to shim your way to the adjustments.
If not, you may need to work your way backward to adjust farther upstream. Ideally the tube and all mirrors would be coplanar. That will solve the height issue. The lateral adjustment you should be able to solve by extending M2 outward toward the front of the machine.
Photos of your machine may provide additional insight.
Many of us have replaced some of these parts to facilitate alignment…
If you have the standard head, ensure the center of the hole is the center of the mirror… This is my original head, you can see the hole is offset to allow for the screw adjustments…
It’s not a crime if it doesn’t hit m3 perfectly, at this point in the alignment it’s more important that it’s going down the center of the lens tube and hitting the lens at its center…
If the beam hits the lens off center it will come out at an angle (like it went in)… either hitting the nozzle or giving you a cut that is not 90॰ or perpendicular to the table.
Have/can you checked it from m3 down to the center of the tube/lens and table ?