steering rack seal

[storm grey]

i need a new seal for the rack which is leaking .i changed it a couple of years ago but for some reason its leaking again (pain) any ideas were is the best place to get one part no ho293 i got the last one from clever trever .but they want £9 to post it which is the same cost as the seal only a very small part.

[phillpot]

If you know the dimensions someone like these might be able to help ?