Philco 90 mystery connector

[37silverstreak]

Hey everyone,
I'm working on my newest project, a model 90. It's a mid production one with the single 47 output tube. the serial number is 912648 and it has this Fahnestock connector on it near the speaker plug. Anyone have any ideas what this might be for? while cleaning the chassis I found that someone had scratched into the surface "magnetic spkr" or something on that order next to it. It's faint and hard to read even with a magnifying glass. Any ideas? Thanks!
Kevin

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