Just acquired a late 1940s Magnavox AM/SW/Phono Console Today!

[Electronic M]

Originally Posted by init4fun

Something to consider here, if sorting the wiring in the arm doesn't bring back the sound;

The typical failure of old carts is not that they fail electrically, but physically. Meaning, the soft parts that allow the needle's vibrations to shake the electrical pieces dry out and become solid. If it's a crystal cart the crystals themselves solidify with age, and old magnetic carts don't fare much better. In other words, electrically good is not proof of a working cart, making vibrations into amplifyable electrical representations of sounds is

I agree continuity isn't a definitive check of a cartridge....However if you read between the lines it sounds like he did an AC voltage test on the cart. If it produces AC voltage in proportion to stylus movement in a groove (or rubbing a finger tip on it...I know it's not the best thing to do) then its at least not dead...
Granted carts do dry out and get into a state where, while not dead, audio distortion is intolerably bad.
The best test is actually listening to it's output.