[PPCFreak]

The volume slider has a plastic tab that sticks out and when you re-assemble the 6700, you have to make sure the slider on the side (part that is on the outside of the phone) is in the middle. There is a channel for the volume slider to rest in. If the outside slider is not in the center when you snap the motherboard into place, it will break off the tab that sticks out.
I broke one on a a board so speak from experience. Not a huge deal as I hardly ever use the outside volume slider anyway....and it does not keep the unit from working at all. Just lets the plastic volume slider slide up and down at will (no resistance to it).