Thanks guys

The seals are the same as for the flap selector, so yes, it is a standard part.

There is no source of original parts though – the conical seals will be easy enough to make – something like the Sealjet process will work.

The teeny tiny ones that are part of the valve are a different story. Makeable, but tricky!

Thanks Bruce..Will look into it.Still awstruck on the complexities of British assemblies..
Hi Whitley Project..
Try these out here and see what suits you best..
http://www.freebyte.com/cad/cad.htm
Basicly CAD is just like Tech Drawing of old but instead of rulers,squares and compasses all the lines are computer generated.Here is a screencap of CAD with one of our designs..All do different things better than others.