Why Does My Printer Sometimes Print A Pink Shadow Type Effect On Black Text/imag

I'm having a problem where black text and images will often print with a pink hazy edge or sort of shadow effect. Sometimes this will occur accross the whole page, which usually consists of several of the same image - for sublimation purposes, or sometimes just on part of the page. On screen all looks fine. I've printed test pages, cleaned heads etc and again all looks fine when tested. It doesn't do it everytime, just seemingly random times, although it is happening more and more. I've attached a scan of one of the sheets where it has done it (sorry upside down)and indicated one of the images that has this problem, you can see that quite a few of the ones above and below it do not have this issue. Can you tell me what the issue may be and what I should do about it. It is imperative for the work that lines/edges are crisp and clear. Would very much appreciate any advise that can be given.