Hmmm... Here's something interesting. After detaching more and more of the room, I've discovered that the problem is, in fact with the pistol/grenade pannel. I dunno what I did, but I've managed to create little "ghost faces"



I have 4 faces selected (I did a drag select over that tiny exposed line segment after hiding the surrounding faces), but no normals are showing, despite the visualize normals being turned on. It appears to be a triangle defined by two points. Very strange. I think my original strategy applies to this situation. Nuke that entire panel and start over, this time being more careful how i extrude edges, and weild verticies.