It's why I dug up the diagram.
Hold part #12 and part # 7 with small pliers and they unthread (there aren't any threads shown on the drawing where the parts meet, but they're there).
Another tip, push the PINS towards the back (the wire end) one at a time. Find something like a split pin starter tool or use fine-point needle nose pliers to hold and push them back out. The center rubber part CAN come out but it tears (don't ask me how I know). Then you switch black and white pins and reassemble. There's a white sleave you put on LAST before threading the base #7 back on, part #3, I think - you'll know it when you see it, it goes INSIDE the base of part #7, THEN part #12 threads on.
I put the plug into the jack on the dash to hold in place while I reassembled everything. Oh, and don't forget to put the locking ring back on before assembly (no, I didn't).
NB