Kitchen mixer tap

[Dave]

I have what I believe is called a mono mixer tap, similar to the one shown at

some way down the page and is marked Bristol. My problem is that it was diagnosed as having a split lower O ring. I bought 6 new look alikes from a reputable plumbers merchants as spares and have just split a second one trying to put the tap back together. At this point, I must say that I am no newwbie to O rings in both hydraulic and pneumatic systems, so it must be something I am not doing right in my plumbing attempts.

With the neck of the tap out, there is a groove for a PTFE washer (split for obvious reason) another swaged groove for the top O ring and another for a lower one (this is the one that I have split,) but what I can't understand is that the base of the swan neck has a dish shape in it, possibly for a third O ring. As I was not present when the tap was pulled apart, I am not sure what was there in the first place. All I know is that he had to fish out the remains on an O ring. And it was in only 2 parts.

Taking another look at it, one tap feeds from the bottom of the swan neck and the other through the holes above the lower O ring.

Is there a knack I don't know of fitting these O rings, or am I not using enough grease?

Dave Going to fit the last door handle I wrote about last week (the redundant screw holes needing filling.)

[John]

Are you sure the groove is for an o-ring? On mine it is for the retaining grub screw to locate into to stop the neck coming out.

[Dave]

There is no grub screw on this tap, it is held together with nut that screws down after the neck is inserted.

Dave