Britony Combi 80 SE. Help please.

[Mick Stupp]

Well! Basically I am having a battle of wills with my 8 yr old Britony combi 80 SE boiler.
It suddenly started (well not quite suddenly, it just started and got worse because I just put bigger bowls underneath,) leaking. It eventually seemed to be leaking from just about every point that you can think of. I am not a plumber, but I am an extremely competent D.I.Y.er. I have also worked in the motor trade, and am pretty much a hands on type of guy.
So far I have replaced most of the seals. the valve in the right hand hydraulic block, and the complete left hand hydraulic block. I really thought that I had cracked it tonight, but... It is leaking from the air separator valve on the top of the plastic pump housing. I know that I can buy a replacement for it but... I just can't fathom out how to get the damned thing out. I am loathe to get too heavy with it, in case I break the plastic housing, thus needing to buy a complete pump. I am unemployed, so basically I cannot afford to just go out and buy a new boiler and have it fitted, (much as I would like to.) I think that when we were sold this boiler, we were sold a "pup."
So if any of you guys could help me, I would be extremely grateful.

[Puddle]

The auto air vent/separator just unscrews from pump housing,once you get new part,you will see

[Mick Stupp]

Many thanks for your reply.
Maybe I was just being too careful, afraid to break the housing...

Edit. Now that I know it unscrews, I just attacked it again with waterpump pliers and it came out.
I was afraid to try too hard before, because I wasn't too sure if it unscrewed or was fastened in by some devious means...
Thanks very much for the info...