The pilot light of my Aga is on but not the main burner

SOURCE: main burner will not ignite Tempstar(NTC5075BFD1)

try cleaning the pilot oriffice it sounds like the flame is weak

SOURCE: Propane patio heater ignition problem

I would change the thermocouple and here is why:

The thermocouple is the pilot's, well, co-pilot! It is the electronic device that senses if the pilot flame is hot enough to sustain burning the gas fuel from the burner. If the thermocouple thinks it's safe, then it keeps open the main gas valve located in the pilot assembly. If the thermocouple does not sense enough heat from the pilot flame (such as when the pilot is out), then the thermocouple shuts off the gas valve to the burners.
How the Thermocouple Works
So what is this thing and how does it work? Well the thermocouple (technically called a thermocouple junction) is a device that contains two metal wires welded at the ends and placed inside a protective metal case. The thermocouple sensor is found at the business end of the pilot flame and is designed to be placed in the hottest part of the flame. The other end is connected to the pilot valve body. As the thermocouple heats up, it produces a small amount of electricity and when it gets hot enough from the pilot, send a signal to open the gas valve by using a solenoid operated by a 24 volt transformer. The thermocouple calls the shots, and by converting heat to an electrical signal, it allows the gas valve to open or close. Once the gas valve is open, gas is then constantly supplied to the pilot and as required for the gas burners (as called for by the thermostat). If the pilot goes out, then the thermocouple gets cold and produces no electric signal to open the gas valve's solenoid and the gas valve shuts off the gas supply to the pilot and burners

SOURCE: I have a 6 gal Atwood hot water heater. I can

Kenny did you change the thermo coupler?

SOURCE: Pilot lights, main burner will not. Replaced gas valve, no change

I had a problem with the same stove,same model no. etc. Needed new valve. Will replace tomorrow, I will let you know how I make out.

SOURCE: Pilot relighting Garland Commercial range

The main burner valve is the oven valve. The pilot will be next to the burner and you either have to insert a long shiskabob stick ( lit) into the hole or lift up on the bottom of the oven (inside) and you will see the pilot.