Bottom of Mug always faded

[mugsofglory]

Hi all - I am having an issue recently where every time I press a mug or bottle (differing heat elements) I am getting a faded look at the bottom half of my mug/bottle.
Printouts look fine, I've tried differing ways for my mug e.g. in leftwards, and rightwards) - same issue.

Any ideas or is it a case of buying a new element?

[Mrteajunkie]

Warm the mugs first.

Either put in some hot water and dry or pour in an inch of hot water and dry prior to pressing.

I use a tepenyaki plate grill thing to warm the bases.