re-wiring the music centre turntable

this must sound a bit basic to most of you but we all have to start somewhere!!

I have a panasonic 'music centre' from 1976 which I want to use for playing vinyl into my 'modern' separates system.

I know nothing much about the innards of hifi but presume it must be possible to run new wires from somewhere around the turntable/pickup arm or even from the cartridge to the phono input sockets on the back of my receiver. (I think it should be possible and doubtless simpler to get an adaptor lead to go from the DIN out of my music centre to one of the other inputs on the receiver but they're all full)

So can any of you tell me or point me to info on how to go about doing this please - or any alternative suggestions for getting the old sound source into the new system??