Finally I decided to take action. My first thought was to simply try to clear the obstruction through the top, i.e., the easy way. It’s not easy to clear out plumbing slime, however, so I was going to have to remove pipes and clear them manually. I do this on a regular basis in the bathroom, so I had some sense of what to expect, and of course, it wasn’t pretty. It turns out that the connecting pipe had loosened and descended and was no longer at the proper angle to maximize the flow of water. After I fixed that, I reamed the pipe and cleaned the grate, and lo and behold, we had flow. I love when that happens.
I think we need to regularly run water down that drain to keep things moving along. Until the next time, thanks for reading.