Gas dryer does not fire up

Here is a manual: https://dl.dropbox.com/u/8010163/Maytag%20Neptune%20Drying%20Center%20%28DC%29%20Re pair%20Service%20Manual.pdf
You can test the different components of the gas system and find the problem. Most problems are from dirt build-up and a burned out safety. When it gets very dirty the main safety blows, but often the hi-limit is bad, too. The contacts weld shut on the hi-limit and then the safety blows. Tear it down, clean it, and find the blown safety and it will run fine. You must be very thorough and take out the ducts and wash them out or it will fail again.