Thanks Rosco! I'm gonna go cheap on the lamp, but, to quote Emily Littella: "Nevermind!" As (bad) luck would have it, I installed TWO washers on two of the screws. They fit together so nicely I didn't even notice it. I went to remove one of the screws to go to Home Depot tonight and lo and behold: the washers had duplicated!!!!
Thanks everybody. Moderator could please delete this somewhat embarrassing thread!
Paul