Thanks for the reply. The leaking fitting was the one that was stripped, and it looked like someone had applied some kind of sealer on the threads to get it to hold. Of course, the line that was leaking was the one that was hardest to get to, once again proving Murphy's law! I'm realizing now that the trick is on installation to get it just tight enough to not leak, but not too tight so as to strip the threads. One of the axioms of plumbing is never to use dissimilar metals in contact with eachother,so I wonder why MB would have designed this set up, when a simpler o-ring set up would have worked. Do you recommend some anti-sieze
paste on the threads for assembly?
My strategy for this one shall be: 1) find good used cooler
2) find bad used cooler and weld fitting, 3) bite the bullet
buying a new one.