I have a Camray 2 oil fired boiler with a riello 40 g5 burner. It has had an updated pump fitted to it a while back 3007811. It wasn't firing up despite the fan and damper working and sparking up. My father took the pump to pieces and now it keeps jamming. I have turned the pump manually with the cover off and the crescent shaped piece (which floats free) jams in the gears of the other two cogs. Is it worn out and would that have been the reason for a lack of fuel to the burner when it wasn't jamming. Any help much appreciated.