Samsung MultiXpress X4 Series Service Manual page 508

4. Troubleshooting
4) Yellow Background
a) Mark a point on the screw with the pen.
b) Rotate the 'R' screw 90 degrees in a counterclockwise direction. (This is the 1.2 mm align adjustment.)
c) Execute a copy or scan job to check the image improvement.
d) Repeat step 2,3 for improvement.
NOTE
If the image does not improve by three attempts, please stop the adjustment.
4-258 Copyright© 1995-2017 SAMSUNG. All rights reserved.