laser calibrate

[taffio]

I have recently bought a new laser for my v4 ps2 (magic 3)
but some games takes ages to load and some not at all inc fifa 2003 original dvd game, i have been told that the eye needs to be adjusted can, anyone tell me how.
my last laser that was playing up i had adjusted and the white plastic adjuster cog was moved does anyone know where that has to be ??