Hey jaknight, thanks for the bump. I thought I'd already closed this.
I replaced the sprockets and chain. Noise is completely gone. :-) Thanks for help, folks.
While I was replacing the chain, I bunged up (for the first time) a master link. Normally, I'm very careful not to press the plate in too far, but that's just what I did. Fortunately, I had a spare master link on hand, so I just pulled the over pressed one. Then, I pressed a new one on.
Short story long, I discovered that if you over press the plate just a bit too much on a master link, you get a very stiff link.
