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They could drain the water and turn it up on its side and see where it is wet.This is one disadvantage of a full foam tub, you just have to start digging into the foam.
Ok... couple things.First, turns out this happened right after they drained and refilled. I don't know if this is coincidence, but I find it interesting at the least.Second, they turned it off and let it leak for a few hours... they believe it stopped. Pulled off a couple panels (I was wrong they hadn't done that before) and nothing is wet. Do they start digging towards the jet(s) in question?
If the tub leaks down to a certain level than stops, then I'd suspect that anything above the waterline would be suspect- I'd start looking at that level. If it is potentially any number of jets located around the tub, I'd maybe start by carefully probing into the foam with something like a stiff wire- that might save them a lot of aggravation pulling foam unecessairly. Personally, if it was me, I'd probably call in a pro- they have techniques to locate leaks more efficiently than us untrained people. If you get someone who works on that model spa, they might know of weak point to check first. Plus, I've seen photos of foam removal- it's looks to be a pretty messy job!