Make sure that the color regis unit front spring has not become weak and allows the unit to back up away from the transfer belt.
Try the auto color registration adjustment
Also what is the PM count and Cycle? SC45-20, 45-21 can also be caused by worned out consumables. The color registration patterns are too light for the sensors to detect patterns properly due to worn out drums or developer, transfer belt etc.
If the machine is past the pm do the pm and re run the color reg adj.
