I recently replaced my PRV and it is set at 70 psi. when we open a faucet, etc the pressure drops to 40 psi is this normal or could something be wrong? prior to the old prv going bad we never noticed any drop in pressure while showering. Upon taking the old prv apart i notice a large portion of one of the rubber o-rings was missing. could this be blocking flow in our meter? not sure what to do any suggestions?