Hello and Welcome Stuart.
You could try
www.powerhouse.uk. They are brilliant with Brembo stuff and are the only UK stockists of a lot of the stuff.
Ducati Paddy is also a very helpful chap
http://www.ducatipaddy.com/
I'm just wondering if the spring of which you speak is actually the little button insert that pushes on the microswitch button, as on the early coffin masters?
If so Moto Rapido stock them for about 60p, but it's below their minimum order to post, so you might have to think of something else you need to make the order up.