it's in service menu under head alignment.
there are 2 physical (bias and vertical) alignments, and 2 electronic ( horizontal and bi-directional) and should be done in that order.
You'll need a (preferably thin) vinyl, phillips screwdriver and i think it's a 1.5mm allen key (hex wrench)
the bias prints colums of ink from each head in 2 passes, you look to where the passes meet. If they align, move on. If they do not meet up in the middle, you have to loosen the 3 screws on the top of the head by about a turn so the head can move. there is a small opening on the front of the print carriage that leads to a screw pushing against the head, thats the 1.5mm allen. Turn the screw, tighten at least 2 screws on the heads, test print again. if its worse, turn it the other way, if its better, keep going. repeat until they align.
Next up vertical, it prints horizontal rows from each head, one magenta, one cyan. these should align as well. if not, again loosen the 3 screws, but only on the right head, as the left head is fixed in place vertically. there is a white knob on the front of the head that when turned pulls forward or pushes back the head. adjust, tighten, test print. repeat until aligned.
Horizontal. test print, choose the most aligned numbers from the graph it prints, change the values in the corresponding settings.
Bi-directional - same as vertical.
If the lines from the test prints are fuzzy and hard to tell what is or isn't aligned, you won't really be able to adjust.
