Not on every page, but once in a while, the last sentence on a page
will have a space in the middle, as if it is trying to make room for
the page number below it. Now, I've tried double-clicking on the page
number and moving the page number down the page a bit, but this
doesn't seem to cure the problem.

I can move the last sentence to the next page and usually this takes
care of it. But it's a hassle. Often I have to backspace the moved
sentence to get it to begin in the right spot on the page. And of
course, it sometimes moves the final sentence on the next page into
position to create the same problem again!  I tried
Format/Paragraph/Line and Page Breaks/Page break before pagination,
but that didn't seem to do the trick. There's obviously a simple
answer to this perplexing problem that probably involves limiting
where the last sentence of a page will be, but I haven't figured it
out.

Thanks,
Clif