"Clifford Heath" wrote in message ...

.. . .

I've disassembled a couple of mono HP laser printers. The fuser is heated
by a long halogen lamp inside a thin-walled metal (aluminium?) tube, which
is coated with something very slick, perhaps PTFE. The thermo switch is
just an on-off bi-metal thing that rides against the fuser tube - with
surprisingly little signs of wear on the ones I took apart.

When I got "fuser error" on an ancient mono HP Laserjet, I also found that
fusers were expensive, although I did also turn up some place that sold
replacement heating elements. For that model, there was a ceramic element
and a thermistor in the fuser.

However, my tests and measurements showed no obvious problem with the fuser
and I came to the conclusion that the problem was in the controller board. I
established that power was getting supplied to the heater, but ended up
replacing the control board with one from another printer which itself was
actually working but had seen a lot more use than the first one.

For the record, the repaired Laserjet still works today - it is way over 20
years old now.