Dryer gas valve solenoid coil kit. The kit includes both 2 and 3 wire coils. If the dryer does not heat or heats intermittently the gas valve coils may be defective.
Dryer thermistor. This thermistor should read approximately 50,000 (50K) Ohms of resistance at 77 degrees Fahrenheit. *Note that it is not in the heating circuit so it likely will not be the cause of a dryer heating problem. It can however effect cycle times or cause a fault if defective.
Dryer lint screen at door opening. Proper air flow is critical to dryer operation so the filter should be cleaned before every load. Replace the filter if it has any tears or rips in it.
High limit thermostat