On Fri, 02 Jan 2009 11:30:08 +0000 (GMT), "Dave Liquorice"
wrote:

On Fri, 02 Jan 2009 10:23:55 GMT, Cicero wrote:

But the black seal appears pristine!

Whats that white blob? B-)

Dunno. Since I took the unit out to photograph I've removed the seal
and given it a good wash. (I looked in Focus and Homebase, plus a
couple of local hardware (mom & pop type) stores, but no dice.)

Is the seal fairly soft and plyable to mould to the bottom of the cistern,

Seems so. It's only approximately four years old after all! I've got
exactly the same unit in the downstairs loo and that one is NOT
dribbling. (Downstairs has had a lot less use, though.)

still smooth with no indents from gunk on the cistern?

Well, there are ~some~ very faint marks when one looks really closely,
but you have to wipe it really clean and hold it under the light to
see.

If it really is in
good condition I think I'd remove it from the siphon check that the seat
and it are clean and smooth, rotate it a bit, refit and do the same for
the cistern. When refiting to the cistern does it feel as if the seal is
being compressed?

On the latter point, yes, it does feel like it's being compressed.
I'll try what you suggest re rotating.

I would say that the most likely cause of your problem is simply that
the water level is too high

Except that the OP has stated that the cisterm will completely empty if
left with the supply isolated for a day or two. Water level to high
causing an overflow wouldn't do that.

I agree with that latter point since the water level drops right down
if the inflow valve is closed.

I sent an email to FastPart this morning, asking them whether the seal
is available separately, but I haven't heard back yet. Probably shut
until Monday. There MUST surely be a replacement seal available,
otherwise what's the point of making the top part quick-release to
gain access?

MM