From what i understand of the mod, (assuming it's the same one) the backside of the nozzle portion of the tappet is sanded down a bit positioning the nozzle slightly forward on the tappet plate. So when the nozzle moves forward it travels furthur into the bucking portion of the chamber getting a slightly better seal. However, without modifying the "fin" portion of the tappet, the nozzle stays slightly forward even though the tappet gets pulled back.
Let me put it this way.
Pre-mod: The leading edge of the "fin", that contacts the sector arm, and the tip of the nozzle is "x" distance. The sector spins and pushes the tappet back "y" distance clearing the feed portion of the hop chamber exactly. BB loads in, tappet gets released nozzle goes forward chambering the bb.
Post-mod: tappet is sanded (we'll say .2mm). So now the nozzle sits slightly forward and the distance from fin to tip is x + .2mm. Now when the sector contacts the "fin" and moves the tappet back the same y distance but the nozzle sits .2mm forward. That's .2mm into the feed path blocking the bbs from loading.
The sector clip basically enlarges that tiny little sector arm pulling the tappet back and as long as possible. You can also use a tiny bushing and fix it to the arm.
http://www.rsov.com/index.php?target...roduct_id=1478