Looks like the machine itself was giving problems as even though they changed the element I was still having issues of ink not transferring fully either on left side rim or right side rim of the mug. With testing in showroom.
So they've given me their test model for now until a new one is back in stock.
But he did say the print I was doing is notoriously difficult. Full black with coloured text 3mm from top and bottom of mug.