kenmore 79801 gas dryer, will start n heat up but if the door is opened soon after starting it will not start again for a long time and the start control button does not make any noise. The dryer will also run and heat up for maybe a 1/2 hr or longer sometimes and then shuts off and can not be restarted for quite awhile, sometimes hours, sometimes longer. Would appreciate some sugestions on how to solve my problem, Thank you