If the leak is at the compression fitting the only fix I'm aware of is to tighten the fitting more. The
manual illustration appears to show a fitting that is able to be tightened. My '38 is as shown in the illustration. If you have something different I don't know what to tell you. There should be no "O" ring in the assembly. Maybe if someone else has had the same problem they will be able to help you more. Good luck.