GPG wrote:
I seem to have to keep having to replace them after an astonishingly short
time. The latest has just packed up after about 15 months (so out of
warranty, I imagine). Is there any future in trying to take them apart, or
otherwise try to repair them?

I would hazard that if there is nothing obvious just chuck it out
(i would not flaff about with something that has electricity and water
in such proximity but then I am a wuss) as a new one is in the under a
£5 range, of course you could be , really trendy, and go for an £80 kettle.
Ours is , at least, 11 years old and is still working fine it is
used at least six times a day