Oven mercury valve..
I changed the mercury valve, the one that has the temp sensor next to the pilot.
The sensor is attached to the TAB next to the pilot. Choose a mid range oven temp, get a grill lighter and heat the sensor. If the main burner lights up, then adjust the tab, so the pilot heats it up when you choose a higher oven temperature( the pilot should increase heat). If the main burner does not lights up, check or change the valve.
Mine is a CNG.
Hope is not too confusing.
Marco