Hi Chris,

Many thanks for the very detailed reply, you are a star !

The tool you describe sounds a bit like a hand made rug tool I have
(its a small hook on a handle basically), I assume that this is just
used to get the O ring (at the back of the white plastic housing) out,
not to put it in... am I right? Otherwise I'll have to contact AL as
you say.

My local plumbers had a tool they recommended for this that looked (to
me) a bit like pliers. I couldn't see how that would help. I'll go and
find the name of it, perhaps it would work.....

I have another AL mixer that's leaking (a manual model 409) that has
had very little use in an en suite bathroom. And its started leaking.
I think I may have installed that in 2002 or 2003 possibly - I suppose
I need a new cart for that one too ! I'll be ruined at this rate....
more so !

Thanks again for everyone's help,

Tom