Looks like a 7 to me for the first digit .
code sometimes seen after FON, i.e. 2586G).
1942 907, 910, 923, 2004, 2005, 7000ish (i.e. 7119) - all 'Banner' logo.
1942 H (letter code sometimes seen after FON, i.e. 7116H). Range 5xxxH to 8xxxH
1943 Range generally 9xx to 22xx, depending on the model.
1944 Range generally 22xx to 29XX, depending on the model, some with no FON.
1945 1xx to 10xx, but many with no FON.
1946 n/a ('Banner' logo no longer used, now script logo with no banner).
1947 700s to 1000s
1948 1100s to 3700s ('Script' logo no longer used, block logo used.)
1949 2000s
1950 3000s to 5000s
1951 6000s to 9000s