Uneven flame

The flame is uneven along the burner

The Essentials Guide: an uneven (asymmetrical) flame means "There might be a blockage in your burner. Try cleaning it out with compressed air." Blow it over the burner from inside the oven, then through the gas terminal with the knob pushed in (help centre), and run it for 30 minutes. Still uneven: a full cylinder, then a spare regulator. Wind also changes how the flame looks.