I never followed up, but it did just pull out. There are six spring clips, one at each end and two each on the top and bottom. It sounds like it is going to break the plastic end cap as it comes out, but the cap was undamaged.
For those who may read this thread later, the control center does not have an enclosure around it, and there are wires hanging down between the main wiring bundle and each of the switches and lights. The PCB looks like late-1960's tech, and the light bulbs are enclosed in small cardboard tubes. There is no multi-plug to quickly disconnect the whole unit to take it to a workbench to do maintenance. I'm not looking forward to disconnecting it, since I'll have to mark every wire and every connector so I can put them back on correctly.
I'll put some photos up when I take if off the wall to change the light bulbs. It's just been too hot this weekend to work on the trailer after work.