HP Designjet 500ps not printing greys

[Martin225]

Hi,  Does anyone know why my My HP Design jet 500ps isn't printing greys and the blacks look green-ish when I do test/calibration prints direct from the printer? Also when I print black and white photos from the computer they come out with a blue-ish tint. (I have made sure the print settings are on greyscale).

I have attached photos of the test/calibration prints direct from the printer along with a stock photo of a dog that I tried to print where the grey background came out blue-ish purple. 

I have replaced the blue and black print heads to see if that was the problem but it didn't work.

Thanks, 

Martin. 

Thank you. 

[D Hook]

From the photos, it looks like you have some poor performing printheads.  I'd start there.