Robbie,  Your request for more information about the resistor in the
motor governor mechanism had to be put on hold for the weekend as I
traveled to Chicago for a wonderful AMICA meeting hosted by the
Krughoff's.  As many MMDer's know, this collection is indeed one of the
finest in the world.

The information on the exact replacement resistor was easily found in
an article that I wrote for the AMICA Bulletin published in July 1979
under the title "Ampico B Drawer Problems".  The resistor, Mallory
2HJ400, is slightly shorter in length than the original and can thus
fit into the limited mounting space.  The lead wires are too short and
therefore must be lengthened, but that is not a problem. The bare wire
must be covered in a heat-tolerant insulating "spaghetti".

This is a 400-ohm resistor.  The table on page 44 of the "1929 Service
Manual" lists the governor resistance as 360 ohms for 110 volt
applications.  Reading the service manual from page 41 through 46 gives
a clear explanation of the governor operation and how the resistor is
employed.  The adjustable resistance unit is also adequately explained.

During prolonged continuous play (hours), the adjustable resistance
unit produces heat, which is dissipated under the soundboard.  The
protective cage covering this resistor will be warm to the touch --
not hot.

The tempo lever will become pleasantly warm.  If the cover shielding
the governor resistor is removed and a person touches the resistor,
they will be burned.  If the original resistor is burned out, the tempo
lever will never noticeably heat up.  The motor itself just barely gets
warm after hours of operation.

No other electrical devises should be added to this system.  Damp
chasers, piano desk lamps -- anything -- will totally ruin the balance
of the system and must not be added.

If there is any more heat build up other than what I have just
described, something is wrong which could be dangerous.  The tempo
lever will start to feel warm after just a few rolls if things are
working normally.  After 15 minutes of play, if the tempo lever is
not noticeably warm, the governor resistance is burned out.  A shorted
resistor is highly unlikely.  A complete short will be indicated by
loss of tempo control, and the inability to make the motor slow down.
A partial short will quickly result in burn out.

Bob Taylor