So I just got a new keg. I went down to tap it and I noticed that I can't find the rubber washer (mine was gray and its a washer but also extends into the coupler) that goes in between the coupler and the CO2 line. When I take my stuff apart to clean I just unscrew the CO2 nipple instead of trying to get the co2 line off of it. Well I guess the little washer that is inside the nipple has fallen out. Where could I get another one? I've tried googling and I can't seem to find anything. I don't know exactly what its called. Could I just replace it with a regular washer (like the kind I am using on my beer lines)? Thanks