what have you tried to isolate the problem so far?
i notice that you have bonded global contact and then 300 contact sets. many of the contact sets are overriding the bonded contact sets. not necessarily a bad thing but not needed. i would have expected your problem to solve so there must be a contact or 2 that you missed.
first thing i'd do is try soft springs or a frequency analysis to find out which parts aren't connected.
or you can do it the manual way, add a few parts to your assembly at a time with one of them fixed and a gravity load, and you'll find the component that isn't attached to the rest.
something you may want to consider is simplifying some of these parts.