Electric motors made by the Master Electirc Company were used
and a number of small mills, including the Nichols Hand Miller.
Master Electric was acquired by Reliance, which was recently
acquired by Balder.  Their renewal parts group still has 
oil seals for the co-shaft.  No other parts are available.

The motors are identified by the Style ID on the name plate.
I have the part numbers for the oil seals for three Style IDs,
and my best guess as to when they were manufactured.  

1940's 

For ID 113129 the Co shaft seal is PN 60212822A

1950's

For ID 143963 the Co shaft seal is PN 60212822A

1960's

For ID 245130 the Co Shaft seal is PN 60212823A

These three Style ID's were used on Nichols Mills, and are 1 HP and
350 rpm output.  The Nichols mills used several other Master Gear Motors
with different Style IDs, so this list not in anyway exhaustive.

The file master_gear_motor.jpg is a parts drawing of the gear box
for the 113129 motor.

Contact Info for Balder is:

   Baldor-Dodge-Reliance
   Mechanical Renewal Parts
   P: 864-297-4160
   F: 864-284-5041 or 1- 800-848-2727