Sony HP-810 stereo system has no sound coming out of the record player

[Electronic M]

Touch the signal hot lead or connect a known good audio source to see if it gets through. If it does you've got a dead NOS cartridge (not in heard of at that vintage and somewhat common on 50s-60s carts). The cables don't pass signal, and the radio works fine then something between there and the output of the function switch has failed (dead phono preamp?).