User`s guide

Troubleshooting Expansion Post Connectors - 23
Expansion Post Connectors
The LaserWriter 600/630 has several cable receptacles that are
secured to the printer by finned post connectors. The fins expand
when you insert the connector, but once the connector is installed
it can be difficult to remove.
If you cannot remove these connectors with your fingers, try
small bent-nose pliers, a 5 mm nut driver, or grip-rings forced
around the post.
Caution: The cable receptacles are keyed. If you install them
upside-down, they will not couple properly.