Thermidor Gas Cooktop

The back left burner is not getting any gas. What part do I need to fix this problem. The igniter sparks, but without gas it does not light.

Sounds like the potetionmeter according to what I have read,
I am replacing the burner parts including the above hard to find part for my old range/oven. I am having to use a dremel in order to get the old ones off. PITA…