Thanks for the advice. I reached in and checked around the lens and it felt completely dry. I also tried a fluorescent dye test around the light and lower bench jets with no noticeable dye making it past those elements. I've called the dealer and will have the service department take a look, but in the meantime I plan to drain the tub all the way down, let the concrete pad dry, then s-l-o-w-l-y fill until I see leakage. I'm hoping to narrow it down to the light, jets, or drain lines. Any other ideas? It would be great to avoid having to dismantle the tile surround (it's modular construction, so not as bad as it sounds) and from having to extract the tub from it's concrete pillbox (much more difficult).