Beav,
Thanks for that info! Only reason I suspect the caliper is that it does decrease markedly when I apply the brakes!
I thought the caliper would leak as well if one of the piston "rings " were absent, but I'm going through a process of elimination. I last month replaced the tired original struts with Koni inserts and new bump-stops, and the upper mounts looked great, as it's been a Callifornia car it's entire life. I've had a shop tell me it was the ball joint, but I replaced them within the last 6 months.
I've used a rubber mallet and dead-blow hammers to try to get any noise. The noise will either be a rattle when passing over rough/broken textures in the blacktop, or a distinct knock when the left front suspension is deflected abruptly, as in bump or hole. I've even replaced the slide pins!!!
Glenn