Zoony. One of the parts nature gave me gave up when I was 35 (no not that one!) and I was fitted with a replacement mechanical aortic valve which will be 40 years old later this year. I reckon it has cycled on and off about 1.5 billion times and seems still to be going strong. I have always wondered how long the warranty lasts.
As far as household replacements are concerned, my boiler is 12 years old and is serviced by the same guy annually. The only problem so far has been about 4 years ago when the pressurisation unit inexplicably lost its charge, was repressurised and has been fine ever since. He advises against changing it yet as it has the same efficiency rating as a newer model.
Other things, if they break down out of warranty, I just buy new ones. I never buy extended warranties, they are a scam. Relative to inflation, most houshold machines are so much cheaper these days that warrranties - which often don't pay out - are as much as 50% of the price of a new machine.
Mike.