first prepaire you for a while of twiking.
what you have to do is like my system: i cut out of 1/8 pressboard squares in the size of the outside of the holder ring, then I put two stripes of tape on the piece and stick the hole thing on the holder ring and tape to the back, ( this prevents the mirror from damage because I dont remove the mirror)
the first wher you do this is the mirror right next to the laser tube and shoot a beam the brown point should be around the middle of this mirror .I marke the middle of the press board with a compass.
then you go on the Y axis and put the press board on this holder ring and move them to the back ( closest to the tube ) and shoot a beam put the settings on about 6 to 8 % shoot just as much that you can see the brown spot it shoud be somewhere around the middle and marke it
then you slide this mirror ( gantry mirror) to the front of the machine
( the farest from the laser tube) and shoot another beam see where it lands
now comes the tricky part you have to adjust the 1st mirror closest to the laser tube to get right on the on the first ( marked spot)
now go back and forth and see if the spots are allway on top of each other.
this way you have alligned the Y axis and take the pressboard off
now you take a piece of tape and put it right on top of the laser head opening move the Y axis to the back and shoot a beam and see where it lands if you dont see any brown spot take a 2inch stripe about 5inch long and hold it just in front of this openeing and shoot a beam maybe shoot a second time this way you see where it lands now come the fiddleling what could take a long time.
to adjust the laser head mirror you have to use the set screws on the second mirror ( gantry mirror) but be carefull dont turn to much just play a bit to see how it works the brown spot should be here around the middle of the openeing on the laserhead, marke it
then move the Y axis to the front of the machine and shoot another beam.
if you are lucky it the two spots are exactly on top of each other if not you have to use the gantry mirror setsrews to bring the second spot right on top of the first one
after they are right on top of each other ( just be paitient) then move the laserhead to the right rear corner and shoot a beam again this should be exactly on top of the other two if not you have to use the gantrymirror setsrews again bit just very little ( on some machines a turn of 1/16 is allredy to much)
now you have to go back after adjusting this spot to the first position left rear and check the spot if it is still there
after all this matches you have to go to the front right corner and try the spot there and do the same like on the other spots .
like I said be patient you will get it right.
my first time took me 4 hours. but now I do it in 20 min.
I hope this helps