Printhead alignment(Flexi-jet4800)

I am trying to perform a successful printhead test on a Flexi-jet 4800... It seems the alignment is out of wack... I am assuming the best way is to do a "manual" alignment... Which I tried to perform but hard to see the white ink... I tried doing an auto alignment but pretty sure it was not able to read it and it was printing beyond the platen(selections?? sheet, roll??). Someone said to use a thin piece of plexiglass which I also tried... I also tried to perform a test on other material but was not successful... I'm hoping someone can help me out... Thank you!...