It's common that the magnetron starts to go weak after a number of years.
Also, the main capacitor in the power supply may be starting to fail.

If you are interested to know what is failing, you can take the microwave
oven over to a local service centre to find out.

From experience, once a microwave oven is more than about 4 years old, I
would not invest very much in servicing it.

--

JANA
_____


wrote in message
oups.com...
Hello,

My microwave oven is old, and has had the usual abuse (spills,
occasional sparks because of foil, etc).

After a few years, I notice that it heats up a cup of water slower than
it used to. Several explanations are possible, but I'm wondering about
this one:
Is the radiation likely to be leaking out into the rest of the kitchen?
Or is it probably something more benign, such as less power being fed
to the oscillator?

Thank you very much!

Ted Shoemaker