Main Burner will not light, pilot on, electrode sparking, 3 led's on?

My pilot lights and stays alight. The electrode continues to spark, however the main burner will not light, when it does eventually light, the main burner sometimes cuts off again and the same thing happens all over again. Its a Glow worm micron 120ff boiler, the three led's are on and the electrode continues to spark. I know the when I tap the unit next to the pcb the burner lights. Faulty burner, igniter?