I have a leak in an upstairs shower. I've traced the problem to the
seal between the drain and the shower floor. There is a flange at the
top of the drain that meets the shower floor. There is a gap between
this flange and the floor. I can pour water directly into the drain
without any leaking problem. The problem is the water getting under
the flange and not into the drain.

I tried repairing this with plumber's putty and the fix lasted for
about 4 months. Eventually, the water washing over the putty lifted a
piece of it and the leak started up again today.

Is there some other way to repair this without having to go in from the
ceiling below?

Thanks for any recommendations.

Jeff