[Bierp]

Well, looks like good news. I pulled the stack, took off the top, back and bottom panels of the washer and fired it up. The leak was coming from the dispenser.



Pardon the off-axis image. This was also taken with the probe. (That thing has been really handy!)

I removed the entire dispenser assembly, cleaned it thoroughly, put it back together and, voila, dry as a bone.

Thanks for all the pointers, everyone.

One sad part is that the water catch pan thingy, while sized to fit the closet, won't fit due to the ground level plumbing of the drain. Ah well, it was useful when I was troubleshooting the issue on the carpet.