Let start by saying that repairing your Whirlpool electric dryer when is not heating, is not a hard a job to do, if you know what to look for.
The heating circuit of the Whirlpool electric dryer consist of the following parts. The timer, the heating element, the hi-limit thermostat, the safety thermostat, the operating thermostat, the temperature switch and the motor centrifugal switch.
If any of these parts fail, the dryer will not heat. Now, most people when the dryer stops heating, replace the heating element or the timer with out checking to make sure that those parts are bad. Rule number one is, don't assume that the part is bad with out checking it with a multimeter.
The first and most important thing you need to do, is to disconnect the dryer from the wall outlet before doing any kind of work on it. Most parts will need to be checked for continuity and the dryer must be disconnected from the wall outlet.
Most of the times the part causing the problem is behind the dryer and you can gain access by removing the back panel.
Remove the back panel on the dryer. Disconnect one of the heating element wires and take a reading between the two terminals on the heating element. The reading should be between 10 and 50 ohms. If the heating element is good, check the hi-limit thermostat by removing one of the wires and checking for continuity. Continuity means, that electricity could pass through the part that you are checking.
The hi-limit usually blows when there is an obstruction on the exhaust hose, so make sure that the exhaust hose is not obstructed when replacing the hi-limit kit.
If the hi-limit thermostat and the heating element are ok, check the operating thermostat. The operating thermostat is in charge of maintaining the temperature inside of the drum at about 150 degrees. You will need to check from the two terminals with the red wires attached on it.
Those where the parts that fail more often in the Whirlpool electric dryer. The timer, the motor centrifugal switch, the temperature switch are a little harder to check because there are may different one. You will need to use your wiring schematic to see how to check them.