Ravenheat RSF 82ET not firing up?

When I turn on the heating on my Ravenheat RSF 82ET instead of getting two clicks and then the flame igniting I now only get one click and not the second and the flame dosen't light, now I've changed the electrode and the electrode cable but still no joy. The printed ignition board (the part in plastic casing with the blue lid) was replaced over 5 years ago so in terms of the age of the boiler its relatively new, so the only things I can think of is the fuse in the printed ignition board or the printed ignition board itself, any help? - Also it my help, but before the boiler stopped working, when I use to turn the heating on and got the two clicks before the flame ignited I'd sometimes get another two or three clicks after that before the flame would reignite itself and this was whlist the heating had been on for over an hour or two?

david
October 2020