Have a GE JES1142SPC01 , less then a year old. And of course I cant find receipt . Starts adding time while heating something up.. i leave it unplugged all the time. When i need something heated up , i plug it in and it beeps and automatically starts with 30 seconds.Then a few seconds later it will beep and add another 30 seconds.this will continue til i unplug microwave. Any ideas ???