Diagnosis
The burner tube orifice or the venturi (the tube mixing air and gas) is partially blocked by a spider web or debris.
How to Fix It
Turn gas off and disconnect propane tank. Remove the griddle top (two people recommended). Locate the affected burner. Use a compressed air can to blast air through the burner tube, both from the orifice end and the air shutter end. Check the small hole in the orifice for debris. Reassemble and test.
If That Didn't Work
The regulator might be failing, but it usually affects all burners. If only one is weak, swap the burner tubes between two positions. If the problem moves, you need a new burner tube.
Heads Up
Orange flame means incomplete combustion, producing carbon monoxide. Do not cook with this until you get a steady blue flame. Ensure the area is well-ventilated during testing.