I don't know how they check em with air as they are vented. Depending where you live, there are folks that repair them, I had it done twice. Riveredge Marina did it the first time and Fishlessman the 2nd time, but I think it was mire a favor.
If you can find the leak, most any aluminum welding shop can fix them.
Check all the welds that would be under the water line, you should see one that is cracked, most likely the nose cone I'll bet.
Here is what happened on mine:
Condensation builds up in the nose and on mine there were baffler or something that traps this moisture and over winter in will freeze and could crack the weld. The Premier factory admitted it was a poor design, they recommend to put a a gallon of recreation anti freeze in each tube (tilt nose down and add anti freeze through the drain plug) then when you store it, store with the nose end tilted down)
Hardest part is finding the leak, we filled the pontoon with water the first time and looked for a drip, once found we saw the weld was cracked.
There might be a way to pressurize the pontoon, but I don't know how they do it, about mid way of the pontoon you might see a poly line, this is the vent.
Any advice on a place that can find and repair a leak in a pontoon log? I was summerizing my toon today and drained about 20 gallons out of one of the logs. I never checked them prior to storing ( I thought the slosh I heard in there was just the gallon of antifreeze that stays in them.)
There is a marine welding shop across from Fays I think, in Gilford that was going to repair a small dent on my pontoon boat. Call M and M boat salvage in Meredith, he can tell you who the guy is. There is a guy in Ashland, NH area that does work for Squam Boat Livery, call them too.
If i can find the Gilford shop number I'll post it.
