Bleeding oil pump?

Danesmoor 26/32 locking out. Think had identified problem as bar pressure had fallen below acceptable level so have now rectified this. Burner now runs for a little while but is still locking out. I am wondering if I now have an air lock and need to know how to get rid of it, in simple terms please. I saw someone do it once but can't remember what I need to do, what pipe to disconnect etc. I know I had to supply him with a receptacle to catch the oil but that's about all.
I have plenty of fuel so its not that, had a new oil pump last January so it shouldn't be that. Can't get anyone out until after Xmas, no heating and no hot water not very pleasant right now.

Katy M
December 2010