Have you tried the site of Son’s and Father’s Hobbies at http://www.sfhobbies.com/sfhobbies/radio/emailus.jsp?
They have very many Sears & Roebuck repair sheets that I’ve never seen anywhere else. They are totally devoted to Silvertone radios and have helped me to identify some very strange looking old radios.
It has been quite some time since I last contacted them and they provide a service for a fee.
They will let you know how much information they have and how much it will cost to obtain it then you decide if you want it or not.