The ignitor glows and the gas flows in the beginning. Then it goes off after it reaches its temperature. The second time it glows and the gas comes on and it works again. Then, the third time and fourth time the ignitor glows, but there is no gas. It switches off, no flame comes on, and the ignitor turns off. So the heat in the drum slowly gets cooler.
Replace the coils on the gas valve, if they are available. If not you would have to replace the whole gas valve. Tom ApplianceEducator.com