I just got a 2001 HotSpot XLSXtra spa and when I filled it up it leaked 25% as fast as the garden hose could fill it. If you faced the control panel/motor access side, the leak was in the exact center of the left side. We drained it and put it up on blocks and dug foam out to expose a big 2 inch or so pipe and no leak there. The water was flowing just "through" the foam and exiting that area I guess. The water drained down to the bottom of the vertical grate on the lower right side (lowest grate except for bottom drain). I guess this is probably the intake for the pump? Anyway, before we dig more foam out (not a fun job - 6 hours of experience already) I thought maybe someone would have an idea of where it was coming from, and maybe we could get a pipe diagram from someone? It is great shape otherwise. Thanks in advance!

The plumbing daigram doesn't show much. If it's at the filter area I would check where the temp sensor goes into the wall. If not there check the light lens from inside the equipment area. These are my best guesses.