:Sounds like Bill Grimm has a good idea. Check riders for the circuitry by looking at different models. Make a note of where all the tube sockets are located & the tube types. Then compare the circuitry to the riders. Thats how I do it & usually I come out real close. Some versions have slight modifications but you won't be too far off. I have a 5009 & that is in the late 40's. Start there & work up and down until you find yours. ALSO make a note of where the TRIMMERS are & which ones are which. Then try(?) to see how the tuner is located & which POSITION. Then turn the set over & compare the parts values & which tubes go to which parts.