Riello RDB1 burner problem?

Please can someone help...I'm freezing!

I have a Riello RDB1 burner.
I recently had a refill of oil but before that the oil had run out and some air got sucket in.
After the refill, I bled the burner, and it seemed to work fine. But I noticed that everytime it needed to fire up (every few minutes) it just wouldn't do it, the house would get cold and I needed to press the red reset button each time to fire it up again.
This went on for a day and a half but now it refuses to fire up at all - when I press the red reset button it tries to fire up but just stops again.
What can I do?
Does it sound like I need a new pump?
Is there any 'homemade' remedy??

Thanks