I have a mysterious leak in a Mustee Part 48.105 installed in 1993. I have recently found a drip leak
after the shower runs about 6 minutes whether some one is in the shower or not (kinda sorta eliminating the shower plan flexing opening a crack). I sealed the drain with a vacuum seal, covered the drain about the size of a pie plate with duct tape and put an inch of water in it from a bucket no leak, over about 3 hours. Then left the drain sealed, filled the pan to about 1" from the top of the pan from the shower itself, no leaks. Removed the seal ran the shower for about 5-6 minutes leak began again. I have inspected the flange around the drain for cracks, searched around the base of the flange from below
, no leak. I have stripped all the caulking around the top of the pan where it meets the tile and replaced the caulk with silicone. This has me completely bamfoozled. Hairline crack, somewhere, nail hole I can't see. Anyone have a suggestion?