Locating replacements for these switches has turned into a nightmare. The wafers are in excellent condition and contacts have seen very little use. The switch is easily disassembled leaving the wafers in the desired switched state but then then they cease to be functioning switches. The only problem is that the shaft has been sheared off on both switches. The knobs are also missing.
Both switches were manufactured by ALPS in Japan. ALPS is still very much in business but their back catalogue does not seem to extend to the 1960s. I may have to purchase modern equivalents and rewire them with the existing resistors OR hopefully with more compact components.
The rotary wafer switches in question are as follows:
Alps 8D 513-3 109-11 and the Alps 8D 513-3 10-11