If you have a red light on the control box and when you push the red button you hear a hummmm then a click then it sounds like a capacitor. They are cheap and you need a 4uh one. However to check its the problem, take the burner out of the boiler and take off the fan housing and the hydraulic ram- just the screw not the oil connection. BE CAREFUL and point the burner head away from anything combustible. Press the red button and give the fan a wee turn with a screw driver- if it spins and fires up, then its the capacitor. Good Luck
Gordon at fix my oil boiler. com, December 2008