Ok, I know there are plenty of posts regarding this issue. My friends whirlpool gas dryer is not heating up. I have not had the chance yet to check it out yet so before i do my question here is what would be the fist step…I’m confused on where to begin. 
You can find the complete troubleshooting instructions in one of our previous posts: http://forum.appliancepartspros.com/dryer-repair/4743-no-heat-gas-dryer.html
All part numbers listed there are good for your dryer as well.
Gene.