I've been thru the tunnels, upper & lower. I've killed the monster, and looted Hoxplox. When I come back to N&Thix, I can't get anything from them, and I don't know where to go next. Does anyone have any suggestions? THANKS.
The stairs up to the next level are to the far north east on the first maintenance tunnel level (see map). There are 4 locked doors leading to the stairs, opened by 4 levers throughout that level.