Older Magic Chef three burner camper range oven combination. Top three burners work correctly. Pilot lights and remains on. Pilot light does not increase in size when thermostat is turned from OFF to desired temperature. Oven will light if external heat source is applied to the pilot tube bulb. Oven burner will remain on as long external heat source is applied to pilot tube bulb. Oven burner will go off when heat source is removed and tube cools. Thermostat has PILOT OFF, OFF, multiple temperature settings, and B (broil). Thermostat has two aluminum tubes coming out back. Small diameter on left side and goes to pilot assembly. Larger tube goes to oven safety valve on back of oven. Thermostat also has a small diameter tube / wire heat sensor that enters the oven through the top of the oven at rear. Pilot burner has been cleaned. Pilot tube removed and cleaned with compressed air. No changes. Any thoughts?