Can you share any pics of the previous test print, wiper, print head, take the cover off the head (2 philips screws) and show the dampers?
What ink are you using (SS21) and are they OEM?
Have you tried a custody or nozzle wash (follow steps and fill the cap with the cleaning fluid (spc-0369) and let it soak for at least 20-30 minutes (max is 90))?
Not to get you worried, but ours did the same thing (for some reason magenta is rough on these machines) before we had to replace our print head after 5 years (got another 2 after that before we replaced the whole machine).
If your looking for a guru, I can recommend Brian Hendricks @ American Print Consultants
www.apcink.com (he's in Sandusky, oh but his hq is in Chambersburg, pa)