Mamiya 6 RF adjustment

[mylek]

Hi,

i'll like to know on which screw i can adjust the vertical RF of my Mamiya 6. It focus properly but most of the time the horizontal are not sharp. To get them focus i neddd to raise my eye and i loose the upper line of the frame with a 75mm.
I read a lot of post concerning the Mamiya 7 but on the 6, there is a 3rd screw.

Thanks!