Special thanks to those who responded.  Should anyone have an
opportunity to work on one of these, here is what I learned.

The Reblitz book offers little beyond the "A" roll tracker bar detail.
A general web search and searching Library of Congress and searching
Amazon came up empty.  Dana Johnson, Johnson Restoration & Supply,
was of great help in providing an internal tubing diagram with details
of the 3-position volume control added to the later models.

The rest is pretty straightforward, including the coin box which is
the standard used on most Seeburg systems.  MMD is a great source for
information and thanks again to all those who participate.

Walt Gerber