This is usually caused by a lack of airflow through the dryer. This is usually caused by a restriction below the lint filter inside the lint duct or in the vent hose leading outside. Sometimes the lint filter can become covered in a clear layer of fabric softener residue also which will restrict air flow. Take the lint filter out and wash it under running warm water and scrub it lightly with a soft bristle brush. Check the vent hose for kinks are sharp bends and straighten them as much as possible. It's also not abnormal for the top and back to get warm or hot to the touch if your drying several loads one after the next.
You could also have a bad thermostat or bad heating element that is causing the dryer to get hot/or over heat. Grounded elements are difficult to diagnose. A technician with an ohm meter is most likely going to be required to check the voltage to the elements to determine where the problem is occurring. If you would like to schedule service, you may do so by logging onto
I hope this information is helpful.