T520 colors banding after new printhead

[bestoday]

Hi

Replaced the printhead on a Designjet T520 due to poor print quality. Initially everything was fine but now have to continually clean the printhead to get a reasonable print quality on all three colors. The diagnostic image shows black streaking & banding on the colors.  Cyan is worst, then Magenta and finally yellow may have one or two black streaks. I can never get it 100% even after all three cleans. It then becomes poor again after capping and being idle for a while.  Suspected the service station, so have also manually cleaned all traces of ink from the wipers/ capping area & brushes that may contaminate the printhead. There isn't any waste ink in the spittoon.

Really appreciate some advice before I replace the service station?  As maybe I am missing something. 

Thanks

[Repairatrooper]

Everyone hates this question, but OEM or 3rd party ink? If you are seeing no ink in the waste container then it is very likely that the service station or the priming pump are not working properly.

[bestoday]

Has always been OEM inks.  By 'waste container' I assume you mean spittoon on the left side? 

Surprisingly, barely a film of ink on the bottom if you put your finger in.

I have seen those fill up with dryed ink on some older Designjets that can be cleaned out

So which one is it, the service station or priming pump or both do you think?

Many thanks for your advice.