^^ Hex screws are the norm for the framelocks like the HD7 and HD12. I've taken mine apart probably a dozen times now fiddling with it. Just make sure you put it back together with the hardened washers against the handle slabs, not the blade. Don't over tighten the bearing pivot! I have already seen a couple Sheepdogs with warped/deformed washers from such! If confident, hammer them back to a flat profile on a vise or similar.
I thought mine was off center on the blade but the entire blade is off center through the whole handle being that the recess for the bearings weren't cut a even depths on per side. Deeper on the G10 side so the blade ends up sitting closer to that side as a whole. The spacing between the standoffs and the adjusted pivot is the same so it might have been intentional.
The drilling in the blade is certainly larger than the detent ball. Mine had some play/slop while in the closed position with about 1/8" of movement at the tip of the blade. There is also the miniscule amount of movement from the lockbar flexing that little bit before the closed detent ball pops out of the blade. Another thing that can cause this is the fact that a small bur/curl along the outer edge of the lockbar insert can prohibit the detent ball from seating all the way in.
Remember that if you modify or file at anything, your warranty on the knife is VOID!