Hi, my boiler stopped working yesterday. Having looked at it, I noticed that it keeps trying to start but the burner never kicks in. I know a bit about car engines so I partially covered the air intake to act like a choke. This worked and the burner fired up. However, the problem has persisted so at the moment I have to choke it every time I want it to come on. Is there a simple fix or should I call an engineer after the raster weekend? Thanks