I took pity on this m/c dumped and had been rained on, half a pint of water
in the lower casing.
I've seen a hose attached to these beasts but took me 5 minutes of head
scratching to discover that secret, as no external hose attachement point.

Powered for 2 seconds, sounded ok but probably an excessive chemically/
ozone smell. Then tipped upside

down
to get in case and water flowed out but had not been enogh to invade the
motor. Needs
Torx 10 and 15 drivers to remove casings.

Fancy looking design appearance but the motor to me looks like the same sort
of vacuum cleaner motor of 30

years ago.
Nothing visibly wrong with stator coils or rotor coils. Resistance
measurements across and between
segments seemed ok. Bit of a noise from the brushes once a revolution, spun
by hand.
Pulled off the spade terminals to unlock and then release the brush
housings. Then spinning the armature with a finger nail against the flow and
gradually increasing the nail angle
a point was reached where one armature segment would catch. Measuring with a
1 to 2 inch micrometer then
the diameter across the commutator was 1.185 inches and 1.192 for the errant
commutator contact strip.
Plenty of life left in the brushes but spark erroded surfaces and broken
leading brush edge.

Why should just one segment be proud? , doesn't seem loose.
Not familiar with this sort of fault. At the moment I am thinking of
spinning in a lathe to bring down this

contact. Point tool or rounded cutter or pointed then round ?
At the moment thinking of grinding back the brushes with a stone about 1.2
inches diameter and then using
commutator bedding stone. Anyone know any better or the pitfalls ? Relieving
the edges of the commutator

strips perhaps with a needle file ?

electronic hints and repair briefs
http://homepages.tcp.co.uk/~diverse