i have a mr12 with two proton regulators.the primary regulator diaphragm cover was smashed in while on loan..where can i get a replacement cover and how much should it be? this is a black plastic with the many equalization holes .i.also noticed rust between the diaphragm membrane and the stainless center of diaphragm..the leaver is made of a bluish metal instead of stainless..is this normal?..thank you..