C1 looks to be a cathode bypass/filter cap..... there's no such thing as a precision lytics in tube electronics....they all were rated -50% +100% capacitance tolerance. A 47uF or if your feeling persnickety a 39uF will both work fine.
40 is part of the old standard.of parts valuing that was on its way out when that set was new...So your not going to find a newly made 40.
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