(ET) Electrak E16 drive motor

[Chris Meier <ChrisM pptvision com>]

I recently had my E16 drive motor in for servicing, where the
bearings & brushes were replaced, terminal insulators replaced,
and the armature undercut.  I installed the motor and ran it for
several 20-30 minutes sessions (in an attempt to let the brushes
'wear' in).  The first time I had installed the drive belts and
let it run with the transmission in neutral.  I noticed at the end
of the session the motor was quite warm to the touch.  So next
time (day later, motor cool to start), I pulled the belts.  Motor
still felt quite warm.  (quite warm = means I can lay my hand
on it, but if it was 10-20 degrees hotter I might not want to...)
Seemed to feel hotter at the brush end, though I didn't try to
accurately measure it.

Since I didn't do this before the motor service, I don't know
how warm they run 'normally'.  Can some of you feed back
to me on how warm your drive motors feel after a similar
run, or after a 30-60 minute mowing session (on flat ground)?
The motor I have has no cooling vents, it's totally sealed.

Another issue, the motor has a vibration that is most notable
at low speeds (contactor throttle settings 1-3 of 7), and seems
to get better at the higher throttle settings.  I don't recall it
vibrating like this before, but it's been most of a year since
I ran it during the non-winter months, so my memory has
faded.  Since I'm a newbie at large DC motor & repair....
is it possible the repair outfit didn't balance the armature?
Is this something to be concerned about at Electrak motor
speeds?

Any other advice?

Thanks, Chris