I have an old KD-291R turntable I'd like to start using more.

The cartridge has four posts coming out the back with four wires soldered to them, at least it looks that way.

This does not seem to match some diagrams I saw at LP Gear, which shows the four posts either plugging into the tonearm ("P mount") or four wires attached to the four plugs ("half inch" -- attach with clips perhaps?)

However they show the P mount as using a screw and nut horizontally through the cartridge, and the half inch attached with two screws vertically up into the headshell. My cartridge attaches with one screw down through the top of the headshell into a threaded hole in the top of the cartrdige.

Can my cartridge be replaced?

Also, I have this now running through a Sony STR-DA4ES into the phono inputs. But volume has to be turned way up to hear well compared with other inputs. What might be up with that?

I'm considering putting the turntable back onto the original Kenwood receiver it came with for now.