My Samsung DV220AGW gas dryer is not drying clothes completely. I have verified exhaust vent is clear and has good flow at outside exhaust vent. I’ve replaced gas coils and verified flame sensor has continuity. Basically, the igniter will start and glow bright glow brightly, the gas opens and the flame ignites, but flame will shutoff after 5-6 seconds. I’ve attached video at link below. Any suggestions on how to isolate problem without just buying replacement parts?