Yellow behaving odd on my 3535

[GusG]

My DC3535 has an odd issue with yellow in that it often prints excessive yellow even after calibration. It isn't consistent but the really odd thing is that when I print a comparison page after calibrating or I print the PS test sheet from CWS it always looks great. I've made a custom output profile with the yellow curve reduced mainly in the lower end and that's a workaround until the machine decides to print properly and then I have a print with too little yellow

Any idea why my yellow is shifting all over the place when printing jobs while calibration comparison pages and PS test pages look fine?