This is informative - I found the problem. The pulling developed fairly quickly, and a casual examination of the brakes didn't reveal any problem. Vigorously shaking the front wheels - on and off the ground - also didn't show anything loose. Just before pulling the wheel for a closer look at the left caliper, I pulled the plastic debris deflector uder the bumper to examine the front bushings of the radius arms (tension struts). The right-hand arm had the nut held on by about two threads, it was so loose. The left-hand one was tight. I torqued them both to spec, ~ 35 lb-ft.

The car now tracks straight and true, handles and rides great, and suspension noises developing for years have disappeared.

Steve