Product review (5 stars): Fixed Dryer.  Saved $800
My dryer stopped providing heat and took a very long time to dry on cool air.  I replaced the solenoids and a few thermal sensors, but, no luck.  After a few internet searches,the igniter seemed to be the next source as it never appeared to heat (get red hot).  I replaced it within a few minutes and it was back to running.  I was very, very happy because if the igniter was not the source, I would have bought a new gas dryer.  If you take your front of your dryer and run it, if the igniter gets red hot, but, the gas never goes on, it is probably the solenoid valves.  If it does not get red hot, it may well be the igniter.