[DaleHCook]

I only have the ability to look at one in Riders at Nostalgiaair.

Why? We have lots of information right here. The OP asked abour "37-620," but did not say if it is code 121, 124, or 125.

For codes 121 and 124, we have the original service manual at:

https://philcoradio.com/library/download...l.%202.pdf

See also Service Bulletin 250 for the electronics at:

https://philcoradio.com/library/download...%20250.pdf

See also page 4 of this issue of the Serviceman:

https://philcoradio.com/library/wp-conte...937-05.pdf

For code 125, the service manual is in Service Bulletin 251-A for the electronics at:

https://philcoradio.com/library/download...20251A.pdf

See also the same Serviceman page linked to above.

For all three codes, the dial drive is in Service Bulletin 231-A at:

https://philcoradio.com/library/download...20231A.pdf

One major resource which many are not aware of is my Philco Service Index, which is very hard to find, but is at:

https://docs.google.com/spreadsheets/d/1...1539072455

Note that although I created the Index, I do not maintain it. I wanted to put it online as a downloadable spreadsheet file, but Phorum management chose to put it online as a Google Sheets spreadsheet. I maintain my local copy of my original spreadsheet to keep it current and correct, but I don't have the time or inclination to maintain the online version as well, so it is missing some additions and corrections.