The crystal is easily removed with a crystal lift, then there is a thin silver retaining ring that comes out. At this point the movement can be tipped up to see the edge of the pillar plate. Removing the hands does not release the dial, and it appears to be fastened to the pillar plate by tabs on the edge of the dial being bent through slots on the periphery of the plate.
The water resistant case appears to be a single piece of injection molded plastic labeled made in Philippines. There are no holes in the dial, nor any plugged holes in the case that I can find.
I'm still at a loss. I'll keep trying if anyone has any other suggestions.
Thanks to all for the help.