I've traced it down to being a Hirose connector, but I can't seem to ID the exact connector. It's a 20pin, and the plug side does have a locking sleeve.
It's on a late 90's Roland PCNC engraver, and I'm wondering if it's either been discontinued, or was a special.
I'm planning on building a new control box, but would prefer to use a new connector and keep the original control box complete, rather than cut the plug of, or change the plug on the engraver.