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did you check on nostalgiaair ?

I don’t see a 10140 but you might try to open a few of the schematics to see if you see similarities in the tube lineup.

also look search under Sparks-Withington Co.

Sparton made at least some of their own tubes. I had one with output tubes that were similar to 45’s but with a different heater voltage,and it was a bit hard to find. There was a workaround to re-wiire the heaters in series to accept 45’s instead. It looks newer than a model that would use 45’s but you never know.