regulator 316091706 (AP2125390)

Frigidaire gas range FGF337AUA converted to propane gas.Noticed recently gas smell and found gas leaking through vent orifice in regulator 316091706 breather. Replaced twice by brand new OEM Electrolux(invenys controls) from different vendors,both of them leaking.Verified by electronic leak detector and detection solution.Is it normal for some gas to escape or recent parts are defective?(Cup on regulator was put on lp position and input pressure 10 in w.c.), may I plug that vent or try Y-68506-AF27 made by Robertshaw Uni-line.Thank you in advance for your response.