Thanks a lot for all of the tips. I had no idea actually why there were two of those set screws on each pad, now I know.

I had wiped the rim with solvent, but since the rim had already been switched I suspected it wouldn't be the problem.

Good for me too though. I totally resisted the urge to toe in the pads in the usual manner, remembering an ebay auction for a pair of these that bore the tell-tale wrench scars. As I recall, the auction didn't go so well for the seller in that case.

Customer apparently wasn't so thrilled that the squeeling persisted. Good thing he doesn't read these tech threads, I'll just hafta tell him they all do this. :->), and so far it's the humid weather excuse which does at least have some merit. Maybe if he just rides his bike in the dirt more often the squeeling would go away.