Update - seems the main fan in the boiler has stopped turning.  If I blow into the red pipe the pilot valve opens and the spark generator sparks - BUT the sp1 on the PCB sparks, none appear at the pilot light.  If I manually light it the pilot lights but the main gas burner does not and as soon as the sparker stops sparking the pilot goes out.  Obviously I will need a new fan but are there others issues here too?
                 Max  p
                
 March 2012