On 16/09/2016 14:18, Reentrant wrote:
Our gas oven is about 20 years old and I've just had to replace the
thermostat for the third time. The part is getting harder to find and is
consequently way more expensive (around £100) than it used to be.
Next time a new oven might be the better option.

Looking at thermostats for modern gas ovens (£35 or so) the copper tube
and phial/sender all look pretty much the same as mine. Is it possible
to change that - assuming that's what fails - rather than the whole
thing which includes the gas tap assembly?

Maybe it would need calibrating somehow but I'm not sure if it's
pre-pressurised. Guess I could take the old one apart but that may be
why it's failed if it lost pressure ...

I suspect the amount of valve movement is similar. Why not take your old
one part and investigate? The fault might not be obvious.

You might find some old "new stock" on ebay in the mean time for next time!