Beko DRCS68W not heating?

HI again i tried timed heating for longer and it still glows red hot for about 2 seconds and then the elements cut out ,there are 4 elements within the housing 2 measure 20 ohms and 2 measure 47 ohms.the top cut out or thermistor measures 20 k ohms
and the bottom one is s/c i have thoroughly hoovered out all fluff from element and filter etc.the top cut out is addressed by 2 x red wires and the bottom by 2 blue wires .my guess is that the elements are all ok!the drum rotates and there is a blower but i do not know why the elements are not on ?can anyone help?
Fred