UPDATE: I played with it some more and discovered that removing the torx screw on the visor mount releases the visor. (The two phillips screws - in addition to being nigh impossible to remove, they were so tight - didn't need to be removed.) I saw that the little plastic clip in which the metal visor rod rotates was split (assuming it's not supposed to be), so the metal spins in it a little too freely. Couldn't figure out how to remove it, but was able to pry it apart a little more, enough to get some blue threadlock inside it. After about a half-hour, I tested it, and it seems to be working. I'll take it easy until it cures - supposedly after 24 hours. Hoping it works, but I suspect I'll have to repeat the procedure in the future. But now that I know how to do it ....