ASTATIC, not artistic! The salt crystal cartridge is probably cracked or damaged from moisture and age. This is common. They can be rebuilt at www.west-techservices.com. New and alternative ones can also be used. The wiring may also be faulty. If you can get continuity for both of the wires, then it's the crystal that's at fault. After you have your cartridge rebuilt or obtain a new cartridge, use only a 3 mil diamond needle. Saphire is okay, but chips with bits of steel in the record from those records that were played with steel needles originally. Diamond is very difficult to obtain, but sounds beautiful. 3 mil is a must. Anything smaller will damage records and will sound terrible because it'll hit the bottom of the groove instead of riding snugly in the sides of the groove. LP needles are definitely a no-no. NEVER use LP needles. What I do is actually remove the gem from one needle and then fit it into the one I need to use. This is rather tedious and difficult, but sometimes it's necessary. The above web site should have what you need, though, including in needles. I currently have my Zenith Cobra cartridge on my 1940 Silvertone phonograph (forgot model number..it's a fine one that can cut records and has a radio) fitted with a 3 mil diamond needle. Records are velvety smooth and don't wear. Even records that were from an over-used master sound great. If you use a smaller needle, sometimes these records can give a funny swishing-swirling sound. The music is BEAUTIFUL. It is unbelievable. Almost like an LP, but without all of the treble (I love the clarity of LPs). Has lots of bass, though.
Thomas