Quoted from DNO: The tricky one is the B/W ones with the white plate. You need to loosen the lower screw, then the plate is 2 pieces, that slide to move the bottom of the front piece.
It looks un-adjustable at first glance.
Actually, these are the only ones I find truly adjustable. I have had no problem with my pins with that mechanism.
Quoted from DNO:All of them have this adjustment. (moving the ring forward or back)
Just moving the ring forward or back gets you close but you also need to move slightly down as well. Obviously, this can be achieved by drilling new holes...just wondering what people do in that case. Do you just adjust front to back and leave it or drill new holes so it can be moved up or down?