Sure sounds like restricted ink flow due to particle build up in the dampers, especially after 4 years of use. I recommend replacing the Ink Selector Unit (box containing the set of dampers), as well as the wiper blade, then manually cleaning the printer's capping station, flushing box and bottom of the print head, following our instructions, here: http://www.inkjetmall.com/tech/content.php?133-Printer-Cleaning-and-Preventative-Maintenance
We have worked with Compass Micro over the years, and feel they're a good resource for getting replacement parts.
You will need to follow instructions for replacing the selector unit, and you can get the repair manual from www.2manuals.com
I hope this helps!
Best regards~ Dana