whirlpool gas dryer

[SIZE=3]My whirlpool gas dryer, the heat only turns on for the first 5 to 10 minutes, then the heat turned off (the machine is still running, give cool air only). I can see the flame burning through the hole in front. The flame won’t turn on again right after I restart the dryer; it only turned on after I wait for it to cool down for a while (give heat only 5 to 10 minutes again). Can you tell what’s wrong with my dryer?[/SIZE]