Hey just noticed that on RTS perceptor the best way to get his back pack and arms to sit the most securely are as follows:
You can see the top of the pin that the wheel that his arms attach to pivots on. If you position the backpack so that pin is just underneath the corners of what could be considered his shoulders (right beside his head) than it will sit the best i found.
or maybe mine just has some looser connections. but for those that might have this problem this should help
http://www.seibertron.com/transformers/toys/reveal-the-shield/perceptor/2280/1/91/
the pin im referring to is right above the vehicle mirror
