how can i stop dryer tripping my cu rcd?

dryer(white knight c767) trips out the cu rcd when i turn dryer on.the motor/drum can be switched on only in cool mode of the dryers settings/dial.is there a fault in the heating element?the trip button on the back of the dryer is not cutting out so im guessing there is a live to earth fault.sometimes i can get my rcd to stay on so i dont think it is an overload or major fault.what do you think?