Mitsibushi PU-P1.6VGAA . I was called out to this unit fault today and dignosed a couple of pinhole leaks on top of the accumalator between the factory soldered joint and the accumalator body. I have tried to braze using silver solder and flux but holes keep reappearing. Am i wasting my time trying to braze steel & copper ? or is there another fix. Replacing the accumalator looks like a major pain.