Diagnosis
The infinite sparking for a single burner points to a faulty infinite switch for that specific burner or a grounding issue in that burner's receptacle.
How to Fix It
Ensure the burner cap and base are seated perfectly. Any misalignment can prevent proper grounding and cause continuous sparking. Clean any food debris from the receptacle.
If That Didn't Work
The infinite switch (the control knob's internal component) for that burner is likely defective. It sends continuous power to the spark module. This switch requires replacement.
Heads Up
The spark module itself is a single unit for all burners. If others spark correctly, the module is functional. The fault is isolated to that burner's circuit.