Streaks in Print / Patchy Print

We are having issues with our UV rotary machine as when we print solid areas of colour we keep have streaks in the print.

The nozzle test patter Ln does not show any issues and shoild it show a nozzle out a quick clean and they are back.

We have had a engineer out already and have changed alot of parts, including inks pumps, long needle filters, one way ink valves, disc filters and solenoids but we have not seen an improvement.

Any ideas of what could be causing this and what we could do to fix the issue?

I have attached some images of some of the prints l done.

 

Hi sir
I will send you a document for troubleshooting here but The uploaded file does not have an allowed extension.