Loose blower wheel causes the dryer to over heat and shut down the control thermostat prematurely causing the dryer to be excessively hot on top and take a long time to dry the clothes.
The wheel is fine, not stripped, fully secured, and turning properly. airflow from the unit seems normal, only not hot enough.
I am convinced this is some type of sensor or control issue.
The "short cycling" explanation sounds most viable.
Is it true that this heating circuit has a coil, a controlling thermostat (front of housing), hi temp thermostat (above coil), and a fuse (beside coil), and that's it?