All the modules have various plugs/sockets hanging down from them that need to be plugged into adjacent plugs/sockets. These are usually "held" up under the module for transport with hooks, Velcro, or tucked into adjacent wiring. Having crawled around under the entire last to setups and connected plugs/sockets, I can tell you that it is very difficult to find all those wires tucked away under the module especially in the dark.

I am working on a campaign to get module owners to release all plugs/sockets under their modules BEFORE inserting the legs and standing them up. That includes the yard, especially the yard, as there are many plugs/sockets under there. At the same time, be sure to pull out the turntable control panel, as this has to be done before the legs are inserted.