When a dryer gets too hot it usually has to do with the
cycle thermostat or disruption of airflow.
The
cycle thermostat is located on the blower housing so if smallest bit of air is escaping before it gets back to the blower wheel, the
cycle thermostat will stay closed allowing power to continue to the element.
The only way for the air to go elsewhere is if the drum drops due to the
support rollers or the
front and rear felt wearing out.
You might also check out the seal on the
lint screen to see that it isnt cracked or worn.
After you have checked all the seals and support rollers you can take a probe type
pocket thermometer and poke it through the vent as close as you can to the air coming out to see if its shutting down at the temperature indicated on the thermostat.
Your thermostat should open at 155 degrees farenheit.