Cause

Colour registration sensor (C-4661 - Yellow, C-4662 Magenta, C-4663 - Cyan, C-4664 Black)

Resolution

Step 1.

Step 2.
Power the machine OFF from the main switch leaving the sub switch ON.
Turn main power switch ON while pressing the Utility/Counter key. Keep holding it till the comes up in Service mode.
-02 process adjustment
-02 drum peculiarity
-06 toner revert all on
-02 gamma automatic adjust (wait for adjustment to complete)

Step 3.
-01 Machine Adjustment
-01 Printer Adjustment
-10 Colour Registration Adjustment (wait for adjustment to complete)
When completed exit out of service mode.