Unplug the cartridge. One of the wires is GND the other audio.
Touch the audio wire with your finger with the volume up abt 1/3.
You should get a very loud hum. If you do its the cartridge, if not
its further down the line. The wires are quite thin to the tone arm.
Easy to break or get pinched. If its in the amp you will need to
either trace or inject to find the problem usually. No big deal but you
will need a manual. Its a good learning event !
73 Zeno
LFOD !