On Tue, 19 Aug 2008 05:35:09 -0700 (PDT), chudford
wrote:

It is easy to change the diaphram as the top of the syphon can be
removed without disturbing the inlet and outlet connections.

11p way down the bottom of this page
http://www.bes.co.uk/products/119.asp
but not worth it if you are not buying anything else.

I bought 2 at a pound each from our local DIY shop - I was most surprised when
he said they had them...

Geo