The most common failure item is the gas valve coil(s)
Warning! To avoid personal injury or even death, always disconnect your appliance from its power source--that is, unplug it or break the connection at the circuit breaker or fuse box--before you do any troubleshooting or repair work on your appliance. Also, because some components may have sharp edges, use caution while working on your appliance.
Below are some links provided by, www.repairclinic.com
. This can assist you with diagnosis, parts ordering and replacement.
Dryer parts breakdown link:
Coil illustration link:
If your dryer doesn't heat, check these:IgniterGas valve coils
Modern gas dryers use an electric igniter to ignite the gas from the gas valve. When it's working properly, the igniter glows bright orange. When it burns out, the dryer tumbles but there's no heat because the gas can't ignite. When the igniter burns out, you need to replace it. If the igniter is held by a tension bracket, you very well may need to replace the bracket too.
The igniter is inside the dryer housing, near the bottom front, usually in a cone-shaped metal tube (the force cone). It's about 2 inches long. It's mounted to the far end of the burner tube, and it has two wires attached to it--or to the tension bracket, if there is one.
Gas valve coils
Watch the igniter. Does it glow bright orange, then shut off without igniting the gas? (When the gas ignites there's a large blue flame.) If so, there may be defective coils on the gas valve. Mounted on the top of modern gas valves, there are black electrical coils. The coils, when energized, open the gas valve. If one or more of the coils are defective, the valve doesn't open and the gas cannot ignite. Because it's often difficult to properly test the coils, it's usually best to replace both (all) of them at the same time.