Given the combination of the (rare in North America) vertical WW
cement resistor and cutoff temperature values this looks like the kind
of part that's easy enough to source in volume but almost impossible
in small quantities.

So I see!

Also it's a safety device. You might be best off (or at least safest)
approaching the OEM for a repair part. There's clearly something else
major wrong, so it may not be worth fixing.

It was due to a wiring fault, since cleared up. I bypassed the fuse and the
uint powers up and looks to be OK.

You could try to cobb something together out of a couple 5W resistors
and a thermal cutoff with some ceramic cement, at your own risk, of
course.

If I was going to use this, for example, on my bench as a diagnostic tool
where I would have a hand on The Switch when it was being operated, I'd have
no qualms about cobbing together such a safety device. But for sale and
installation into a user's business--no way.

So it's kinda critical I get a replacement somehow. I'll contact those
manufacturers you mentioned and ask for samples. The equipment manufacturer
said that to repair this unit (the wiring fault is a common field install
error) would cost more than a new unit. Clearly marketing spin and or
outright lie, we now know. I'll ask about a replacement but not hopeful...

Thanks, SP for your insight.

Bests,
Dave