cant light my power flue inset wall fire?

I havent used my fire all summer. Pilot light wont stay lit, heard it could be thermocouple.Fire is 2 years old, flue goes through the wall, electric fan with it. Looked at thermocouple,it's got 2 pen tip size bits either side of the pilot flame, it looks like one unit, it looks connected to a couple of pipes. is it a easy job to do? thanks Dixie