Momchu

This is the 2nd time I had my Girard RV tankless water heater blow out a hole in the copper elbow area. I contacted Girard to get the replacement the first time it happened but this time I’m thinking about repairing it instead of paying $700 to replace it. What do any of you fellow RVer’s recommend for fixing it? Copper elbow or some kind of patch? And do you think JB WELD could possibly work over a patch? Any idea’s would be greatly appreciated!! thanks, Mary S