1. Remove your MMC cartridge/stylus.
2. Press play, and connect your multimeter (VDC) - one probe to chassis, and one probe testing each one of the 9-pin female sockets - see if there's any voltage there in any of the sockets.
3. If there is DC voltage, then don't connect the 9-pin male-lead into the socket.
4. The male connector has only line-out (no DC voltage), so you do not want to introduce DC onto that connection.
5. Because the MMC is now out, you can trace the finger connections on the tracking-arm to the 9-pin female connector. Use your multimeter in the Ohms or Continuity function. Make a diagram, and write them down.
6. Post that diagram back on the forum here.
Learn from the mistakes of others - you'll not live long enough to make them all yourself!