Woohoo! I did it myself.
I've been waiting and waiting for Art to unclog the drain. His first advice was to lessen the shower flow and use less water to give it time to drain.
Well it was getting to the point where now the water was beginning to pool around his feet, too.
He was planning to get a metal snake to put down the pipe and unclog it.
I poured Liquid Plumber down the drain a couple of times and it didn't do the trick at all.
I decided enough was enough. I used a screw driver to take off the drain cover. What I saw was disgusting! There was all kinds of blackish gray mold mixed with hair, etc. I had to yank it out and clean it. Then I plunged and pulled out a bit more.
Wow! Suddenly, it started draining perfectly! I don't think I needed to use the Liquid Plumber before. It just needed cleaning and plunging.
Art just added some bleach to kill whatever biota was left.
He's very proud of me for figuring it out myself. I just told him, "By the way... I'm thinking of hanging that new clock on the familyroom wall by myself, too. I'll bet I can do it. If I add a couple more holes in the wall to get it perfect, no problem. Don't you think?"
Ho! Ho! Do I hear him going downstairs?
Postscript: I just snuck down and checked. He's already put up the wall clock and is now sanding down the sticky door so it'll close more easily. I wonder what other chores we need to get done.