I just completed putting one of these back together, not a single trigger version, however. Ithaca didn't spare any effort making sure EVERYTHING was staked in, and I can't say it was a terribly friendly gun to work on.
But, I bet most of them still work. There is a lot to like about this simple design.
Wonder what it would cost to produce this same gun today?
Good luck with the repair. Please, let us know what it was when you get it sorted. Mine had a balky safety, it was actually riding on the top strap instead of being centered in the safety slide. A little tweak was all it took.
Best,
Ted