Riello 40 G3B is not feedin oil?

My burner is locking out after startup - it gets to ignition stage (yes there is a spark) but does not ignite , it just locks out - when I check I find that there is no evidence of kerosine being emmited from the spray jet (new one fitted) so I suspect the pump is defective but I have no way to verify this... any ideas - BTW there are no leaks or faulty seals that I can find.

Martin.