Mottling on Karat 46 Plus DI press

Hi, I am having a serious problem with mottling on the above press. It is happening on all weight stocks however it is the same brand paper so it could be the stock that is at fault. True to form the paper supplier is saying its not their paper. I have tried different speeds, temperatures but it still seem to be there. When I wash the blankets and start to run its very faint but after approx 500 sheets its so bad I have to wash the blankets again. Any help would be greatly appreciated. Many thanks

 

Sorted thanks, after trying everything it turns out its the paper - Heidelberg came up with the answer I knew I should have bought a SM.