SZ670N disassembly - Please help with WWAN-unit cables

I recently disassembled my trusty sz670n, mainly to try my hand at the process and to clean it up a bit along the way. I've built desktops before but this is my first try at a laptop, so I followed the service guide religiously, kept my screws sorted and took care to make notes of things to remember along the way. Come time to put it back together, of course I missed something and now find myself a little stuck.

Specifically, there are two coaxial cables that connect to the WWAN unit, a black and a gray one, labelled "main" and "aux" respectively. The gray one connects to the wlan antenna, but I can't for the life of me figure out where the black one goes :/ The WWAN unit in the service manual only appears to have one coaxial cable connected to it (the gray one). I've also searched the net quite thoroughly, but most of the disassembly guides relating to SZ models deal with the fan/hd, so the pics cover a rather opposite side of the machine.

Attached are some pics of the pesky cable in question. I vaguely recall it coming up through the USB cover sheet like in the second picture, but I may well be mistaken. Any pointers at all would be much appreciated!