Alan,
One of mine split and I had it replaced under warranty. However, they replaced both so I think I still have a slightly used spare. Problem is, I am currently in Kuwait until 25 July, so I can't nip out to the garage and check to see if the wife has been "tidying up"!!! If you can hang on until I get back you might be in luck.
Why no warranty claim on yours, they're new aren't they?