Turn off the water supply first. Next, turn off the inlet ball valve and open the test cocks. Then close the outlet ball valve. Remove the interior pieces from the 765, then place the O-Ring around the bonnet. Fitt the poppet into the bonnet, and thread the bonnet into the PVB. Make sure to hand tighten only! Replace the brass canopy and tighten the nut on top with a wrench. Turn on the water supply, and open the inlet valve first, then the outlet valve.