This issue is seen commonly with older machines or machines that are used frequently. The result is most commonly referred to as a rainbow effect.
Often the result is a blob of CMYK shapes repeating.
Another symptom is a series of small vertical lines repeating throughout the print.
The problem is the print head is having trouble printing where it is suppose to. The cause is the
build up of ink residue over time. To correct the problem the ink residue needs to be removed.
First make sure the Encoder Strip is completely clean. Make sure the spring still holds the
Encoder Strip with out any slack.
Next make sure that the bars that support the Carriage are clean and free of residue. Oil the
bars after cleaning and make sure the Print Head Carriage glides smoothly on the rails.
Keeping the Encoder Strip clean and the Carriage bars clean and oiled is an ongoing
maintenance procedure. It should be preformed as much as once a week. The following is
something that takes time to build up and does not need to be preformed on a regular basis. If
the Rainbow blob or the little vertical lines have started showing up then the Carriage Belt and
the Gear that drives it needs cleaning. Residue is causing the belt to skip which will disorient
the print heads location. To remove the belt from the gear pull the belt over the edge of the gear
and move the print head and the belt will roll off the gear. Use the same technique for putting
the belt back on the gear.
Use a tooth brush and some maintenance cleaning solution to clean the residue out of the teeth
of the gear and the belt.