So far you have narrowed it down to the cartridge or the wire. Next swap R and L on the cart pins. Then you will know for sure if its the cartridge, or the wire.
If its the wire, most likely its not really the wire itself but the connections at either end. Easiest and first, cart pin clips. Could be they aren’t tight enough. Sick a round toothpick into the clip, carefully crimp with pliers. Carefully. Round toothpick prevents flattening and ruining but you still have to be careful.
Rekkid freaks. That's a new one. Which I hope never to see again.
If its the wire, most likely its not really the wire itself but the connections at either end. Easiest and first, cart pin clips. Could be they aren’t tight enough. Sick a round toothpick into the clip, carefully crimp with pliers. Carefully. Round toothpick prevents flattening and ruining but you still have to be careful.
Rekkid freaks. That's a new one. Which I hope never to see again.