I have a FRAM (but AC uses the same fittings) in my 1951 3604 and I got new replacement lines from Jim Carter and had no problems. I'm curious as to where you got your lines. I assumed all of the vendors used the same manufacturer. I'm pretty sure you have the incorrect brass fittings on the canister itself. I restore these old canisters and get new inverted flare fittings at my local Ace Hardware. I cannot get them at any of my FLAPS. If you can't find them locally, send me a private message and I will hook you up. Good luck, Jeff.