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I finally found the leak after a lot of investigation. I ended up buying some kids bubble making solution and just applying it with my fingers to all the areas I thought might be an issue. I started with the balloon attach point, then all the plugs and still nothing (although it took several iterations on the best method to attach the balloon). I built up the vent line fitting with vinyl tape until the balloon fit tightly, then wrapped it with some more vinyl tape and secured with safety wire. After all that checked good, I moved to the z-brackets and there it was. One of the sealed pulled rivets was blowing bubbles. I cleaned it up, covered with vinyl tape and pumped up the tank/balloon. It held for a week without deflating at all. Bingo, now I know the source, but how to fix it…and why. I ran the borescope inside to see if anything looked wrong, but it looked like all the others. I very carefully drilled out the rivet, by first starting with a #40 bit to about half-way down through the thickness of the flanges. I then sucked out all the shavings with a vacuum. I then used #30 drill bit until the head popped off…which worked great. Again, I vacuumed out any shavings. I never even touched the z-bracket hole. Finally, I used a #40 punch a lightly tapped it into the tank. Tink, it fell in. I managed to tip the tank and get it to fall out of the drain hole. It helped that the z-bracket with the leaky rivet was just one rib away from the drain. I checked out the hole with the borescope and it looked perfect, so I tried to scratch up the inside with a paper clip doubled back on itself to help roughen the surface. Then I roughened up the outside of the hole area as well as the rivet. Next, I put the baffle side down, pushed some pro-seal into the hole with a syringe and coated the rivet, pulled it and added some pro-seal to the head. Hopefully this will work…I’ll check later this next week. So, why did the sealed rivet leak. Upon close inspection with a 10X, I could see that it had cracked. I m

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