Most Duo-Art motors run hot-ish in my experience.  I only worry if they
start to smell as though they are cooking.   Roger, since your motor
has been rewound you will get some "newness" smell but that should wear
off in time. 

If the motor was of American manufacture, it's worth mentioning here
that British Standard Wire Gauge (SWG) and American Wire Gauge (AWG)
are not the same, and sometimes when rewinding coils from outside the
UK, a compromise has to be found, if the correct gauge of wire is not
available.  Of course, your rewind company may have access to the Amer-
ican standards, in which case the above does not apply.

I remember we had problems getting magnets rewound for a Mills Violano.
There was no absolute match.  Slightly thicker wire meant we didn't get
the right number of turns on the coil, because there was not enough
room, and we could not achieve the correct impedance.  Slightly thinner
wire meant the correct impedance was achieved with fewer turns, but
with lower magnetic attraction overall.  Complicated isn't it?

Generally, today's modern electric motors are designed to run at higher
temperatures.  Motors from the 20's and 30's did not as a rule; they
were for the most part over-engineered, which is why so many of them
are still in service to-day.

Our Compton Cinema Organ had a Weber Duo-Art coupled to it, and the
steamboat pump and drive motor was remote in the organ chamber.  It
would sometimes be running from 2:00 to 5:30, most of that time with
the piano not being played.  The motor got very hot indeed, but never
failed.

Assuming you are using the correct-size pulleys and the motor bearings
are not partially seized (which can happen, and that is not always
noticed by the rewind company; I've had personal experience of this),
you could try checking the spill valve operation.  It should, if memory
serves, cut in at "power 8" and below to relieve the vacuum tension in
the player and ease the load on the pump and motor.  There may be a
separate spill on the pump which is used to set the overall vacuum
level, but they were not always installed.  Also, if the holes in the
tracker bar have been covered for a long period of time, this will put
extra load on the motor and cause it to get hotter than usual.

If you are satisfied that all is well, then I suggest you just test and
monitor the situation over a period of time, and perhaps have a chat
with the rewind company to get their ideas. 

Cheers,
Paul Camps