Andrew wrote:
I think mine has though.

I forced back the knurled metal 'clips' that held
the gearbox casing together and the gears were fine,
plenty of grease.
I tried connecting the motor to the mains and nothing
happened, not even a buzzing. Resistance across
the power tags a couple of mega-ohms.

Andrew

When it comes to enamel wire and magnetics, the place
where the wire solders to any post, is a weak spot. On
coils at work, that's where I was seeing failures.

Failures elsewhere are still possible. Poor quality wire,
aluminium wire! and so on. They sometimes wind motors with
Al rather than Cu to save a buck. Some pumps use Al.

Also, be aware there are two kinds of motors. AC Mains
motors, and 21VDC motors. Don't connect the wrong kind
right to mains. If the label on the motor admits to
mains AC and is not a DC motor, then go right ahead.
*Never* connect stuff to mains, without some evidence
it's the right thing to do :-) It makes Thor the god
of electricity angry when you do that. Thor will send
the magic smoke.

Paul