Gas dryer would produce heat for short time, then continue to run but with no heat.

Thanks to reports from others, I concluded that most likely the gas ignition coils (one or both) were no longer functioning properly. I replaced both with the 'M' Series New Style Coil Kit which is about 1/2 the price of either coil individually -- yes,true,go figure! The actual replacement took only about 10 minutes. What was most difficult and took the most time was the removal of the front panel of the cabinet -- this was difficult only because there were no instructions in my owner's manual (or any other source I could find) and it took me awhile to figure it out. Now I could do the whole job in about 20 minutes! The detailed instructions from others as to the process of replacing the coils was invaluable -- I don't know if I would have been able to figure that out on my own. But most important was the information that enabled me to diagnose the problem in the first place. Thank you, all you previous comment contributors.