I could live with the problem, but now it's started to go wrong, it's likely to go wrong in other ways as well - and the next one could be more serious (i.e. more expensive)than thinking the Cat's failed.

Second hand ones don't appear to be worth the risk; not much cheaper and still have the risk of being near the end of their life. Plus, rate as hens' teeth.

Serves me right for having a fancy sports car!