Like I said, it's busy in there, ten pounds of xxx in a five pound bag!
When I run up against something like this, I lay the shell out and carefully arrange the stuff so there's no "lumps" and it appears that the shell will fit. Usually, it's something like that big 8-pin connector pressing down and either flexing boards, or supports. You may have to shift stuff slightly, and also consider zip-tying it a couple of places to keep them where you want them.
