Drilling a hole to get access to the 8th hex bolt, and then the cap suddenly popped loose.
The inner cap is surprisingly complex. One small hole has a little filter in it, next to it one has a ball bearing inside. The large black ring at the bottom is also some kind of vent. These all connect to an inner chamber than has a black gasket. And then the rotating unlock mechanism is in the center.
The carrier for the actual sliding lock. It got pent in the removal process. I will monitor it frequently to see if it seems to get weaker or comes loose over time.