So I tried the CSWA practice exam today, did perfect on the drafting and modeling parts, but failed horribly on the assembly problem I had no problem mating all the pieces, but my assembly's center of gravity was not even close  and I have no idea what I messed up :/

So if anyone wants to help out a noob, I'd appreciate any suggestions on sources or if you'd take a look at it and tell me what I did wrong?

this the link:

Certified SOLIDWORKS Associate Exam | SOLIDWORKS