most dryers have a rest on the back which trips out if the element over heats try resting this if you get heat means element is ok if it goes cold again dont keep resting as you could risk a fire ! if it does go cold possible that themarsate is no good but you have no way of checking this and would requre a servie engineer to look at it (not cheap)
howtomendit.com for free repair help, information and advice.
Try fixfault.com to fix tumble dryers.