The good news is that the speaker came! It's an ounce or two heavier than the old one, but not a huge deal. Unfortunately I found that the hole in the enclosure is not perfectly round. It's about 1/4" narrower horizontally. I've got a call out to someone I know who is a woodworker to see the best way to deal with this. The old speaker frame is ever so slightly bent. May very well have been rubber malleted into place.