Printing shadows - doubles

[DubY3]

Hello! Suddenly my printer started printing everything with shadows/double effect.

The ONLY time it doesn't happen is when I print in Black Only ink preference. 

I want to print in color. Even if there is no color and it's like a word doc essay. If I do not choose Black Ink Only it will print with shadow effect.  The doubling happens on words and pictures. Everything!

Things I have already done: 

I've tried different fonts, tried to print from Word vs PDF vs Online. 

Printed from different computer or program.

I've replaced ink, new authentic HP source.

Checked paper make sure right, etc.

Realigned, printed test pages, align pages, clean and reclean print cartridges.

I've restarted printer, unplug everything, tried again.

Cleaned (with clean cloth and water) back rollers.

It is old but I have 4 packs of ink I want to get through first before I replace it!

[Bob_Headrick]

The double printing may be caused by a buildup of ink on the encoder strip.  This is a thin mostly clear strip that has fine lines printed on it used to keep track of where the printhead is located.  If there is ink or debris on the strip it will cause misalignment any time when several passes are printed in the paper.  This will be the case for all color printing (except perhaps in draft mode) and any tall black printing.  

You might try cleaning the encoder strip as shown in the post here.  The encoder strip is fragile, please read and heed the warnings.  Only use water to clean the strip, not alcohol or any other solvents as the fine lines printed on the strip are needed for proper operation of the printer.  Be gentle!