In article ,
MM writes:

Not until I dismantled the motor and housing. The impeller part of the
motor (inside the big round mounting boss) was stuffed full of carpet
fluff. I had to use tweezers to prise some of it out.

However, after a thorough clean and reassembly, the cutting out still
occurs.

Does the motor spin freely by hand (or are bearings stiff)?
Does motor slow down before cutting out? That can be caused
by windings which have been damaged by overheating and start
shorting out.

Could also be knackered brushes, although failure symptoms
are usually a bit different.

Having now dismantled the machine I have not found ANYthing that could
be a thermal fuse, at least, not at the motor end. Inside the handle
there is a small PCB (approx 50mm x 40mm) to which the cables to and
from the switch are connected. The PCB has what looks like a
capacitor, since it's marked uF. It is yellow, rectangular, about 20mm
x 15 x 5.

Probably interferance suppressor.

There is also a resistor and what looks like a voltage
regulator.

Could the thermal protection be an integral part of the motor?

Yes.

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]