Looking for schematic and info for Sargent 21 receiver

[WQ9E]

I have a Sargent 21-MA which will soon go on the bench and I have been unable to find much info about it.  There is a little bit in Moore's book and some of it is repeated on the internet but I have found nothing else.  I was hoping I would find some info in some of my old radio magazines like I did for my Sargent 11-MA but no such luck.

The 21 was made in late 1936 through 1937 and is a 12 tube superhet with a regenerative RF stage.  Mine is missing its power transformer so I would at least like to find out the target B+ value.  Mine is the -MA version which covers 80 Khz. through 30 Mhz. but the -AA (amateur) version is the same except it doesn't have the 2 VLF ranges so info for either model would be most helpful.