Firstly I would like to thank all respondents for their advice regarding
the overheating problem.

As I indicated initially, the motor did not fail prior to removal.  I
simply judged that if I was going to take the trouble to remove the
large box pump and do some work on that, I might as well check the 80-
year-old motor at the same time, to prevent additional failure at some
point in the future.

I was subsequently advised by the engineering firm concerned that the
motor was in fact not likely to stand up to continued usage for any
length of time.  So I had it rewound and reconditioned.  The firm
specialises in rewinds; so I had no qualms about their proposals, or
indeed, their efficiency. It is quite possible that the wire used is of
a different specification and capacity compared to the original.  I am
not technically qualified to say exactly what was done, but the motor
clearly had been completely dismantled, and I could see bright new
windings in it.

I have to say that I simply do not know whether or not it was getting
hot originally.  But it is now, and I must address that concern. 

The three hour test was after re-installation.  During that time I was
making various adjustments in accordance with the Duo-Art service manual.
The outer case of the motor was more than just warm.  It was uncomfort-
ably hot to the touch, although I got no shock, and the connecting
cable was cool.  I am unhappy with the amount of heat going upwards.
There is no baffle or cowling of any sort to divert the hot air.  The
soundboard is getting it all. Added to the under-floor heating in the
wooden house, this all makes the atmosphere very dry.  I had previously
installed two humidifying tubes in order to alleviate some of the dry-
ness, especially under the valve chest and stack.

As I live some distance away from the customer, I have emailed him with
a request to remove the pulley and run the motor for an hour with no
load.  That should determine whether the problem lies in the motor
itself or perhaps in the spill valve.  I should say that the owner had
asked me to soften the overall  playing volume, so my adjustments to
the spill valve may be having some effect here.  The pulley is also
quite tight.  

The pianola is a pedal/electric Steinway Grand. I have rebuilt every-
thing else on the instrument and know that suction levels are good and
that the action is satisfactorily airtight.  I will report again, when
I get results.

Roger Waring,
The Pianola Workshop
Solihull, West Midlands, UK
www.pianola.co.uk