Variation In Colour On Same Sheet

Hi all,

I have printed some business cards on 350gsm ColourPlan Pristine White (Buckram Embossed) and the colour is different from the Operator side to the back of press, i am wondering it the writing head could be dirty but im not sure on how to clean in on a 5600 i know its easy on a 7500/7800 as i have done it. Firstly do you also think writing head it has a brand new pip and blanket when ran, secondly how to do clean the writing head on this press?

Thanks in advance