Any heating and cooling Guys out there? I have a question

The pilot is a small burner so it has small openings in a barrel/tube just behind that flame. Those air for proper fuel air mixture. I'll agree the thermo coupler is the most common fault but... while you're in there, blow all the dust away from the pilot burner assembly.
We've had a vent free gas log fireplace for about 10 years now. Never have replaced any parts. Have had to clean the pilot burner area a few times.